bin/symbols-check.py: add --ignore-symbol argument

This will be used by radv to ignore 'the ac_init_llvm_once' symbol,
which is not part of vulkan-icd-symbols.txt but is required to be
exported to improve interop with radeonsi/vaapi.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Acked-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5648>

bin/symbols-check.py

@@ -88,6 +88,9 @@ def main():
     parser.add_argument('--dumpbin',
                         action='store',
                         help='path to binary (or name in $PATH)')
+    parser.add_argument('--ignore-symbol',
+                        action='append',
+                        help='do not process this symbol')
     args = parser.parse_args()
 
     try:
@@ -147,6 +150,8 @@ def main():
             continue
         if symbol in optional_symbols:
             continue
+        if args.ignore_symbol and symbol in args.ignore_symbol:
+            continue
         if symbol[:2] == '_Z':
             # As ajax found out, the compiler intentionally exports symbols
             # that we explicitely asked it not to export, and we can't do