Introduce postgresql_server_llvmjit macro

This new postgresql_server_llvmjit macro allows extensions to use
whatever server does in regards to llvmjit plugin.

Typically, the same spec file works for a postgresql with and also
without llvmjit enabled, because the byte-compiled files are
packaged based on this macro value.

The macro includes 1 if the postgresql server is compiled with
the llvmjit support and 0 if without.

Related: #1951268

postgresql.spec

@@ -765,6 +765,10 @@ rm $RPM_BUILD_ROOT/%{_datadir}/man/man1/ecpg.1
 EOF
 %endif
 
+# Let plugins use the same llvmjit settings as server has
+cat <<EOF >> $RPM_BUILD_ROOT%macrosdir/macros.%name
+%%postgresql_server_llvmjit %llvmjit
+EOF
 
 %if %test
 	# tests. There are many files included here that are unnecessary,
@@ -1218,6 +1222,9 @@ make -C postgresql-setup-%{setup_version} check
 - Build with a private libpq
   Resolves: #1967918
   (also discussed in Fedora #1905584)
+- Introduce postgresql_server_llvmjit macro to follow jit config of a server in
+  plugins
+  Related: #1951268
 
 * Wed Jun 16 2021 Mohan Boddu <mboddu@redhat.com> - 13.2-7
 - Rebuilt for RHEL 9 BETA for openssl 3.0