treewide: Makefile polishing
It was not compile tested nor run tested.
- Remove PKG_SOURCE to use default tar.xz
Suggested in https://github.com/openwrt/packages/pull/11885#discussion_r412651018
While removing it, I found there are two packages, which are not built currently due to wrong value in DEPENDS.
- Remove variables, which we shouldn't not have. Remove:
PKG_SOURCE_SUBDIR:=$(PKG_NAME)
PKG_BUILD_DIR:=$(BUILD_DIR)/$(PKG_NAME)
Edited by Josef Schlehofer