pylibfdt: Simpler CFLAGS handling

At the moment we have some fiddly code to either pass in make's CPPFLAGS to
setup.py, or have setup.py extract them from the Makefile.  But really the
only thing we need from here is the include paths.  We already know what
include paths we need (libfdt/) so we can just set that directly in
setup.py.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Simon Glass <sjg@chromium.org>

pylibfdt/Makefile.pylibfdt

@@ -5,7 +5,7 @@ PYLIBFDT_srcs = $(PYLIBFDT_srcdir)/libfdt.i
 PYMODULE = $(PYLIBFDT_objdir)/_libfdt.so
 
 define run_setup
-	CPPFLAGS="$(CPPFLAGS)" VERSION="$(dtc_version)"
+	VERSION="$(dtc_version)"
 	$(PYLIBFDT_objdir)/setup.py --quiet $(1)
 endef
 

pylibfdt/setup.py

@@ -5,7 +5,6 @@ setup.py file for SWIG libfdt
 Copyright (C) 2017 Google, Inc.
 Written by Simon Glass <sjg@chromium.org>
 
-C flags to use are provided in CPPFLAGS
 Version is provided in VERSION
 
 If these variables are not given they are parsed from the Makefiles. This
@@ -75,26 +74,24 @@ def GetEnvFromMakefiles():
     makevars = ParseMakefile(os.path.join(basedir, 'Makefile'))
     version = '%s.%s.%s' % (makevars['VERSION'], makevars['PATCHLEVEL'],
                             makevars['SUBLEVEL'])
-    cflags = ['-I%s/libfdt' % basedir]
-    return  version, cflags
+    return version
 
 
 progname = sys.argv[0]
-cflags = os.environ.get('CPPFLAGS', '').split()
 version = os.environ.get('VERSION')
 
 # If we were called directly rather than through our Makefile (which is often
 # the case with Python module installation), read the settings from the
 # Makefile.
-if not all((version, cflags)):
-    version, cflags= GetEnvFromMakefiles()
+if not version:
+    version = GetEnvFromMakefiles()
 
 libfdt_module = Extension(
     '_libfdt',
     sources = ['pylibfdt/libfdt.i'],
+    include_dirs = ['libfdt'],
     libraries = ['fdt'],
     library_dirs = ['libfdt'],
-    extra_compile_args = cflags,
 )
 
 setup(