Accept file names with dashes in PNG-to-C converter.

Tango icon files often have dashes in their names so accept them in png2c
conversion script and simply replace them with underscores to form a C
identifier for the array containing the image data.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66500 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

misc/scripts/png2c.py

@@ -23,7 +23,7 @@ if len(sys.argv) < 2:
 r = re.compile("^([a-zA-Z._][a-zA-Z._0-9]*)[.][pP][nN][gG]$")
 
 for path in sys.argv[1:]:
-        filename = os.path.basename(path)
+        filename = os.path.basename(path).replace('-','_')
         m = r.match(filename)
         # Allow only filenames that make sense
         # as C variable names