Lighttpd

Properly formatted:

gcc -DHAVE_CONFIG_H -DLIBRARY_DIR=\"/usr/local/servers/announceserver/lib\" 
-I. -I. -I.. -D_REENTRANT -DEXTENSIONS -D_FILE_OFFSET_BITS=64 
-D_LARGEFILE_SOURCE -D_LARGE_FILES -g -O2 -Wall -W -Wshadow -pedantic 
-std=gnu99 -MT mod_mysql_vhost_la-mod_mysql_vhost.lo -MD -MP -MF 
.deps/mod_mysql_vhost_la-mod_mysql_vhost.Tpo -c mod_mysql_vhost.c 
-o mod_mysql_vhost_la-mod_mysql_vhost.o

mod_mysql_vhost.c:12:19: mysql.h: No such file or directory
mod_mysql_vhost.c:37: error: syntax error before "MYSQL" 
mod_mysql_vhost.c:37: warning: no semicolon at end of struct or union
mod_mysql_vhost.c:49: error: syntax error before '}' token
mod_mysql_vhost.c:49: warning: type defaults to 'int' in declaration of 'plugin_config'
mod_mysql_vhost.c:49: error: ISO C forbids data definition with no type or storage class
mod_mysql_vhost.c:57: error: syntax error before "plugin_config" 
mod_mysql_vhost.c:57: warning: no semicolon at end of struct or union
mod_mysql_vhost.c:59: warning: type defaults to 'int' in declaration of 'conf'
mod_mysql_vhost.c:59: error: ISO C forbids data definition with no type or storage class
mod_mysql_vhost.c:60: warning: type defaults to 'int' in declaration of 'plugin_data'
mod_mysql_vhost.c:60: error: ISO C forbids data definition with no type or storage class
mod_mysql_vhost.c: In function `mod_mysql_vhost_init':
mod_mysql_vhost.c:72: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c:72: error: (Each undeclared identifier is reported only once
mod_mysql_vhost.c:72: error: for each function it appears in.)
mod_mysql_vhost.c: In function `mod_mysql_vhost_cleanup':
mod_mysql_vhost.c:83: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c:96: error: `s' undeclared (first use in this function)
mod_mysql_vhost.c:100: warning: implicit declaration of function `mysql_close'
mod_mysql_vhost.c: In function `mod_mysql_vhost_connection_data':
mod_mysql_vhost.c:124: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c: In function `mod_mysql_vhost_handle_connection_close':
mod_mysql_vhost.c:147: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c: In function `mod_mysql_vhost_set_defaults':
mod_mysql_vhost.c:172: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c:191: error: `s' undeclared (first use in this function)
mod_mysql_vhost.c:250: warning: implicit declaration of function `mysql_init'
mod_mysql_vhost.c:257: warning: implicit declaration of function `mysql_real_connect'
mod_mysql_vhost.c:259: warning: implicit declaration of function `mysql_error'
mod_mysql_vhost.c: At top level:
mod_mysql_vhost.c:281: error: syntax error before "plugin_data" 
mod_mysql_vhost.c: In function `mod_mysql_vhost_patch_connection':
mod_mysql_vhost.c:283: error: `s' undeclared (first use in this function)
mod_mysql_vhost.c:283: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c:292: error: `srv' undeclared (first use in this function)
mod_mysql_vhost.c:297: error: `con' undeclared (first use in this function)
mod_mysql_vhost.c: In function `mod_mysql_vhost_handle_docroot':
mod_mysql_vhost.c:321: error: `p' undeclared (first use in this function)
mod_mysql_vhost.c:326: error: `MYSQL_ROW' undeclared (first use in this function)
mod_mysql_vhost.c:326: error: syntax error before "row" 
mod_mysql_vhost.c:327: error: `MYSQL_RES' undeclared (first use in this function)
mod_mysql_vhost.c:327: error: `result' undeclared (first use in this function)
mod_mysql_vhost.c:349: warning: implicit declaration of function `mysql_query'
mod_mysql_vhost.c:353: warning: implicit declaration of function `mysql_store_result'
mod_mysql_vhost.c:354: warning: implicit declaration of function `mysql_num_fields'
mod_mysql_vhost.c:355: error: `row' undeclared (first use in this function)
mod_mysql_vhost.c:355: warning: implicit declaration of function `mysql_fetch_row'
mod_mysql_vhost.c:358: warning: implicit declaration of function `mysql_free_result'
gmake: *** [mod_mysql_vhost_la-mod_mysql_vhost.lo] Error 1
gmake: Leaving directory `/usr/local/servers/lighttpd-1.4.13/src'
gmake: *** [all-recursive] Error 1
gmake: Leaving directory `/usr/local/servers/lighttpd-1.4.13'
gmake: *** [all] Error 2
[root@shockerz lighttpd-1.4.13]# 

"mysql.h: No such file or directory" and "-I. -I. -I.."
-> the include paths were not correctly set for some reason?

I have mysql installed on /usr/mysql/
When I use the paths to locate for libraries to /usr/mysql/lib/mysql/ and include dir /usr/mysql/include/mysql/ will not work.
I had the same issue with a other application where the configure was partly not working correctly.

please check if your mysql_config is working correctly

{{
#!ShellExample
$ msyql_config --include
$ msyql_config --cflags
$ mysql_config --libs
}}}

I got the same.

mysql -V
mysql  Ver 14.14 Distrib 5.5.19, for Linux (x86_64) using readline 5.1

MySQL is working fine.

CentOS 5.7 64-bit

Seems to be all ok:

checking for libev support... checking for MySQL support... yes
checking for mysql_config... /usr/bin/mysql_config
checking for MySQL includes at... -I/usr/include/mysql
checking for MySQL libraries at... -L/usr/lib64/mysql -lmysqlclient -lpthread -lz -lm -lrt -lssl -lcrypto -ldl