Description:
------------
php's configure script has multiple places where it filters out -lpthread from $LIBS
before ac_fn_c_try_link

This is likely ok for shared, but causes problems with static libs.
One example of this is when building openssl static.

# pkg-config openssl --libs

-L/usr/src/php-build/install/OpenSSL_1_1_1h/lib -lssl -lz -lcrypto -lpthread -ldl

Problem is, when configure tries to check this rule, it filters out some libs from
what it was told by pkg-config:

(looping through $XXXX_LIBS)
case $ac_ii in
c|c_r|pthread*) ;;
*)
 LIBS="$LIBS -l$ac_ii"
;;
esac
(end loop)

ac_fn_c_try_link

ac_fn_c_try_link basically does:

$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5

and in my case then, results in the following libs:

-lssl -lz -lcrypto -ldl

note -lpthread missing, and the test failing.

I have not managed to find a way around this without modifying the configure file, adding -lpthread where it needs to be.

The rest of the actual build is just fine after manually adding -lpthread to just the relevant tests.