[sr-dev] Re: [kamailio/kamailio] app_python3: evaluate LIBS variable imediately in Makefile (PR #4085)

This PR to fix error messages like ``` [root@nout app_python3]# make clean && make /bin/sh: line 1: --ldflags: command not found /bin/sh: line 1: --ldflags: command not found CC (gcc) [M app_python3.so] app_python3_mod.o CC (gcc) [M app_python3.so] apy_kemi.o CC (gcc) [M app_python3.so] apy_kemi_export.o CC (gcc) [M app_python3.so] python_exec.o CC (gcc) [M app_python3.so] python_msgobj.o CC (gcc) [M app_python3.so] python_support.o LD (gcc) [M app_python3.so] app_python3.so ```