python: whitespace fix for PYTHONPATH

Seems that using += adds a space in the PYTHONPATH.
Could be some other error, but at least this way
it's sure to not leave any spaces.

Thanks @Xuefer.

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

lang/python/files/python-package.mk

@@ -20,8 +20,7 @@ PYTHON:=python$(PYTHON_VERSION)
 HOST_PYTHON_LIB_DIR:=$(STAGING_DIR_HOST)/lib/python$(PYTHON_VERSION)
 HOST_PYTHON_BIN:=$(STAGING_DIR_HOST)/bin/python2
 
-PYTHONPATH:=$(PYTHON_LIB_DIR):$(STAGING_DIR)/$(PYTHON_PKG_DIR)
-PYTHONPATH+=:$(PKG_INSTALL_DIR)/$(PYTHON_PKG_DIR)
+PYTHONPATH:=$(PYTHON_LIB_DIR):$(STAGING_DIR)/$(PYTHON_PKG_DIR):$(PKG_INSTALL_DIR)/$(PYTHON_PKG_DIR)
 define HostPython
 	(	export PYTHONPATH="$(PYTHONPATH)"; \
 		export PYTHONOPTIMIZE=""; \