Reomended steps when updating libraries

Hello, I write you for advice in the better way to update libraries that PHP depends on. For instance, I need to update libpng in a system with Apache 2.0.55 and PHP 4.4.1. I downloaded and compiled libpng. Now I need to install it and that will overwrite files needed by libphp4.so that is at the same time needed by Apache. What is the right order to do the update? is it necessary to recompile PHP or Apache? is it necessary to restart apache? this is the output of 'ldd libphp4.so': libcrypt_i.so.1 => /usr/lib/libcrypt_i.so.1 libldap.so.2 => /usr/local/lib/libldap.so.2 liblber.so.2 => /usr/local/lib/liblber.so.2 libpam.so.1 => /usr/lib/libpam.so.1 libintl.so.1 => /usr/lib/libintl.so.1 libpng.so.3 => /usr/local/lib/libpng.so.3 libz.so => /usr/local/lib/libz.so libjpeg.so.62 => /usr/local/lib/libjpeg.so.62 libssl.so.0.9.7 => /usr/local/ssl/lib/libssl.so.0.9.7 libcrypto.so.0.9.7 => /usr/local/ssl/lib/libcrypto.so.0.9.7 libresolv.so.2 => /usr/lib/libresolv.so.2 libm.so.1 => /usr/lib/libm.so.1 libdl.so.1 => /usr/lib/libdl.so.1 libnsl.so.1 => /usr/lib/libnsl.so.1 libsocket.so.1 => /usr/lib/libsocket.so.1 libc.so.1 => /usr/lib/libc.so.1 libgen.so.1 => /usr/lib/libgen.so.1 libcmd.so.1 => /usr/lib/libcmd.so.1 libgcc_s.so.1 => /usr/local/lib/libgcc_s.so.1 libmp.so.2 => /usr/lib/libmp.so.2 /usr/platform/SUNW,UltraAX-i2/lib/libc_psr.so.1 this is the output of 'ldd httpd': libaprutil-0.so.0 => /apache2/lib/libaprutil-0.so.0 libgdbm.so.3 => /usr/local/lib/libgdbm.so.3 libexpat.so.0 => /apache2/lib/libexpat.so.0 libiconv.so.2 => /usr/local/lib/libiconv.so.2 libapr-0.so.0 => /apache2/lib/libapr-0.so.0 librt.so.1 => /usr/lib/librt.so.1 libm.so.1 => /usr/lib/libm.so.1 libsocket.so.1 => /usr/lib/libsocket.so.1 libnsl.so.1 => /usr/lib/libnsl.so.1 libresolv.so.2 => /usr/lib/libresolv.so.2 libpthread.so.1 => /usr/lib/libpthread.so.1 libdl.so.1 => /usr/lib/libdl.so.1 libc.so.1 => /usr/lib/libc.so.1 libgcc_s.so.1 => /usr/local/lib/libgcc_s.so.1 libaio.so.1 => /usr/lib/libaio.so.1 libmp.so.2 => /usr/lib/libmp.so.2 libthread.so.1 => /usr/lib/libthread.so.1 /usr/platform/SUNW,UltraAX-i2/lib/libc_psr.so.1 Thank you in advance!