build: allow clang 10+ in configure.py

Detected on NetBSD/amd64.

Fixes: #29536

PR-URL: #29541
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

configure.py

@@ -724,7 +724,7 @@ def get_nasm_version(asm):
 
 def get_llvm_version(cc):
   return get_version_helper(
-    cc, r"(^(?:FreeBSD )?clang version|based on LLVM) ([3-9]\.[0-9]+)")
+    cc, r"(^(?:FreeBSD )?clang version|based on LLVM) ([0-9]+\.[0-9]+)")
 
 def get_xcode_version(cc):
   return get_version_helper(