Fix GH-19298 missing libraries for opcache

[remicollet]

From php.m4

Libraries (-l) are appended
either to the global Autoconf LIBS variable or to the specified
"libs-variable" (e.g., *_SHARED_LIBADD) when the extension is shared

[remicollet]

Tested (RPM build) on Fedora 41, 42, RHEL 8, 9, 10 on x86_64 and aarch64

[arnaud-lb]

Thank you @remicollet!