[PATCHv2] build: allow some python variable overrides

[Gustavo Zacarias]

The python variables (settings) are fetched from a running python
interpreter which usually isn't the target one when cross compiling,
hence libraries and flags aren't the same and can pollute the target
build.
Allow some of these variables to be redefined via environment variables
in order to aid cross-compiling.
According to testing python_LDFLAGS and python_LIBDIR should be enough.

Signed-off-by: Gustavo Zacarias <gustavo at zacarias.com.ar>
---
v2:
 * Fix style as pointed by Paul Kölle.
---
 buildtools/wafadmin/Tools/python.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/buildtools/wafadmin/Tools/python.py b/buildtools/wafadmin/Tools/python.py
index ab1e817..35c61c2 100644
--- a/buildtools/wafadmin/Tools/python.py
+++ b/buildtools/wafadmin/Tools/python.py
@@ -193,6 +193,19 @@ MACOSX_DEPLOYMENT_TARGET = %r
 """ % (python, python_prefix, python_SO, python_SYSLIBS, python_LDFLAGS, python_SHLIBS,
 	python_LIBDIR, python_LIBPL, INCLUDEPY, Py_ENABLE_SHARED, python_MACOSX_DEPLOYMENT_TARGET))
 
+	# Allow some python overrides from env vars for cross-compiling
+	os_env = dict(os.environ)
+
+	override_python_LDFLAGS = os_env.get('python_LDFLAGS', None)
+	if override_python_LDFLAGS is not None:
+		conf.log.write("python_LDFLAGS override from environment = %r\n" % (override_python_LDFLAGS))
+		python_LDFLAGS = override_python_LDFLAGS
+
+	override_python_LIBDIR = os_env.get('python_LIBDIR', None)
+	if override_python_LIBDIR is not None:
+		conf.log.write("python_LIBDIR override from environment = %r\n" % (override_python_LIBDIR))
+		python_LIBDIR = override_python_LIBDIR
+
 	if python_MACOSX_DEPLOYMENT_TARGET:
 		conf.env['MACOSX_DEPLOYMENT_TARGET'] = python_MACOSX_DEPLOYMENT_TARGET
 		conf.environ['MACOSX_DEPLOYMENT_TARGET'] = python_MACOSX_DEPLOYMENT_TARGET
-- 
1.8.3.2