Add stdarch to the list of ignored prefixes

contrib/ChangeLog:

	* gcc-changelog/git_commit.py (ignored_prefixes): Add
	'libgrust/rustc-lib/stdarch/'.

Signed-off-by: Owen Avery <[email protected]>

Author: powerboat9

contrib/gcc-changelog/git_commit.py

@@ -151,6 +151,7 @@
     'libffi/',
     'libgo/',
     'libgrust/rustc-lib/core/',
+    'libgrust/rustc-lib/stdarch/',
     'libphobos/libdruntime/',
     'libphobos/src/',
     'libsanitizer/',