gyp: Open the build file with universal-newlines mode

To make sure platform specific newlines ('\r\n' or '\r') are converted
to '\n' which otherwise will fail eval().

This should handle multiple issues reported on syntax error reading
binding.gyp (partial list):

#979
#199
nospaceships/node-net-ping#24
nospaceships/node-net-ping#21
mathiask88/node-snap7#11
node-hid/node-hid#28
xdenser/node-firebird-libfbclient#24

PR-URL: #1053
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

gyp/pylib/gyp/input.py

@@ -231,7 +231,10 @@ def LoadOneBuildFile(build_file_path, data, aux_data, includes,
     return data[build_file_path]
 
   if os.path.exists(build_file_path):
-    build_file_contents = open(build_file_path).read()
+    # Open the build file for read ('r') with universal-newlines mode ('U')
+    # to make sure platform specific newlines ('\r\n' or '\r') are converted to '\n'
+    # which otherwise will fail eval()
+    build_file_contents = open(build_file_path, 'rU').read()
   else:
     raise GypError("%s not found (cwd: %s)" % (build_file_path, os.getcwd()))