scons: allow .inl file extension

Intended for header files which are not meant to be included directly.

Reviewed-by: Bruce Cherniak <bruce.cherniak at intel.com>

scons/custom.py

@@ -281,7 +281,7 @@ def parse_source_list(env, filename, names=None):
                     # cause duplicate actions.
                     f = f[len(cur_srcdir + '/'):]
                 # do not include any headers
-                if f.endswith(tuple(['.h','.hpp'])):
+                if f.endswith(tuple(['.h','.hpp','.inl'])):
                     continue
                 srcs.append(f)