python-packages: Clean up build variables

* Rename PYTHON3_PKG_SETUP_VARS to PYTHON3_PKG_BUILD_VARS, and
  PYTHON3_PKG_SETUP_DIR to PYTHON3_PKG_BUILD_PATH

  The new variable names emphasize that these values apply to the new
  build process.

* Remove PYTHON3_PKG_SETUP_ARGS set to the empty string

  These were set to override the default arguments in the old build
  process and not applicable to the new build process.

Signed-off-by: Jeffery To <jeffery.to@gmail.com>

lang/python/python-pynacl/Makefile

@@ -2,7 +2,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=python-pynacl
 PKG_VERSION:=1.5.0
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PYPI_NAME:=PyNaCl
 PKG_HASH:=8ac7448f09ab85811607bdd21ec2464495ac8b7c66d146bf545b0f08fb9220ba
@@ -13,7 +13,7 @@ PKG_LICENSE_FILES:=LICENSE
 
 PKG_BUILD_DEPENDS:=libffi/host python-cffi/host  # cffi>=1.4.1
 
-PYTHON3_PKG_SETUP_VARS:= SODIUM_INSTALL=system
+PYTHON3_PKG_BUILD_VARS:=SODIUM_INSTALL=system
 
 include ../pypi.mk
 include $(INCLUDE_DIR)/package.mk