$ cat /etc/redhat-release
CentOS release 5.6 (Final)
===
$ './configure' '--enable-fpm' '--enable-mbstring' '--with-mysql' '--with-mysqli' '--with-gd' '--with-curl' '--with-mcrypt' '--with-zlib' '--with-pear' '--with-gmp' '--with-xsl' '--enable-zip' '--disable-fileinfo' '--with-jpeg-dir=/usr/lib/'
...
checking for GD support... yes
checking for the location of libjpeg... no
checking for the location of libpng... no
checking for the location of libXpm... no
...
Thank you for using PHP.
===
$ php -r 'print_r(gd_info());'
Array
(
[GD Version] => bundled (2.0.34 compatible)
[FreeType Support] =>
[T1Lib Support] =>
[GIF Read Support] => 1
[GIF Create Support] => 1
[JPEG Support] =>
[PNG Support] => 1
[WBMP Support] => 1
[XPM Support] =>
[XBM Support] => 1
[JIS-mapped Japanese Font Support] =>
)
===
$ locate libjpeg
/usr/lib/libjpeg.so
/usr/lib/libjpeg.so.62
/usr/lib/libjpeg.so.62.0.0
/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/jre/lib/amd64/libjpeg.so
/usr/lib64/libjpeg.so
/usr/lib64/libjpeg.so.62
/usr/lib64/libjpeg.so.62.0.0
/usr/local/lib/libjpeg.a
/usr/local/lib/libjpeg.la
/usr/local/lib/libjpeg.so
/usr/local/lib/libjpeg.so.8
/usr/local/lib/libjpeg.so.8.3.0
/usr/local/src/jpeg-6b/libjpeg.a
/usr/local/src/jpeg-6b/libjpeg.doc
/usr/local/src/jpeg-8c/libjpeg.la
/usr/local/src/jpeg-8c/libjpeg.map
/usr/local/src/jpeg-8c/libjpeg.txt
/usr/local/src/jpeg-8c/.libs/libjpeg.a
/usr/local/src/jpeg-8c/.libs/libjpeg.la
/usr/local/src/jpeg-8c/.libs/libjpeg.lai
/usr/local/src/jpeg-8c/.libs/libjpeg.so
/usr/local/src/jpeg-8c/.libs/libjpeg.so.8
/usr/local/src/jpeg-8c/.libs/libjpeg.so.8.3.0
/usr/share/doc/libjpeg-6b
/usr/share/doc/libjpeg-devel-6b
/usr/share/doc/libjpeg-6b/README
/usr/share/doc/libjpeg-6b/usage.doc
/usr/share/doc/libjpeg-devel-6b/coderules.doc
/usr/share/doc/libjpeg-devel-6b/example.c
/usr/share/doc/libjpeg-devel-6b/libjpeg.doc
/usr/share/doc/libjpeg-devel-6b/structure.doc
/usr/share/doc/libjpeg-devel-6b/wizard.doc
===
$ ls -l /usr/lib/libjpeg.so*
lrwxrwxrwx 1 root wheel 22 Aug 23 21:34 /usr/lib/libjpeg.so -> /usr/lib/libjpeg.so.62
lrwxrwxrwx 1 root root 17 Dec 14 2010 /usr/lib/libjpeg.so.62 -> libjpeg.so.62.0.0
-rwxr-xr-x 1 root root 134268 Jan 6 2007 /usr/lib/libjpeg.so.62.0.0
===
$ echo $LIBPATH
/usr/lib
===
$ rpm -qa | grep -e libjpeg
libjpeg-devel-6b-37
libjpeg-6b-37
libjpeg-6b-37
===