python,python3: limit underlinking behavior to linux platforms

This change was introduced in commit 1c54e2b0fb to address build
issues on Ubuntu 12.04.

However it was reported to cause issues on Mac OS X.
Report: https://github.com/openwrt/packages/issues/5310

It was also reported that removing this on MacOS X fixes the issue.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python/python3/Makefile

@@ -264,9 +264,13 @@ define Py3Package/python3/filespec
 endef
 
 HOST_LDFLAGS += \
-	-Wl,--no-as-needed -lrt \
 	$$$$(pkg-config --static --libs libcrypto libssl)
 
+ifeq ($(HOST_OS),Linux)
+HOST_LDFLAGS += \
+	-Wl,--no-as-needed -lrt
+endif
+
 HOST_CONFIGURE_ARGS+= \
 	--without-cxx-main \
 	--without-pymalloc \