Drop orphaned strstart()
strnmatch() → strn{case,}cmp()
Drop mem debug stuff that seems only available in ancient uclibc
Always use utf8 in native scripts, drop FF_SCRIPT_IN_LATIN1 env var
NATIVE_CALLBACKS definition is long gone, so remove unused code
Drop remnant of removed --enable-native-callbacks option
Remove GW's personal GWW_TEST defines
GFileAppendFile → g_build_filename

They are equivalent if last argument of GFileAppendFile is false,
which is the case for every call to this func.
Drop obsolete string resource defs
Merge branch 'slimming-5'