databases/py-sqlite3: fix build on GCC architectures

cc -Wno-unused-result -Wsign-compare -DNDEBUG -O2 -pipe -fstack-protector-strong -Wl,-rpath=/usr/local/lib/gcc9 -fno-strict-aliasing -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -fPIC -DMODULE_NAME="sqlite3" -I/usr/local/include -IModules/_sqlite -I/usr/local/include/python3.9 -c _sqlite/cache.c -o build/temp.freebsd-12.2-RELEASE-powerpc-3.9/_sqlite/cache.o
cc1: error: unrecognized command line option "-Wno-unused-result"