Handle CV-qualifiers in __gnu_cxx audit_symbols exclusion

libssl has a _ZK9__gnu_cxx symbol. The K comes from <CV-qualifiers>
below. Adjust the regex to handle all possible qualifiers.

https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangle.CV-qualifiers

Bug: 524722668
Change-Id: Iaedd07cc9249dc8bcdffccc446573a18320880fa
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/98547
Commit-Queue: David Benjamin <davidben@google.com>
Auto-Submit: David Benjamin <davidben@google.com>
Reviewed-by: Lily Chen <chlily@google.com>

util/audit_symbols.go

diff --git a/util/audit_symbols.go b/util/audit_symbols.go
index da23462..13e7f39 100644
--- a/util/audit_symbols.go
+++ b/util/audit_symbols.go
@@ -50,7 +50,7 @@
 	regexp.MustCompile(`^DW\.ref\.__gxx_personality_.*`), // libstdc++ exception handling
 	regexp.MustCompile(`^_Z6memchr.*`),                   // memchr()
 	regexp.MustCompile(`^_Z6strchr.*`),                   // strchr()
-	regexp.MustCompile(`^_ZN9__gnu_cxx.*`),               // __gnu_cxx::
+	regexp.MustCompile(`^_ZNr?V?K?9__gnu_cxx.*`),         // __gnu_cxx::
 	regexp.MustCompile(`^_ZTI.*`),                        // typeinfo
 	regexp.MustCompile(`^_ZTS.*`),                        // typeinfo name
 	regexp.MustCompile(`^_ZTV.*`),                        // vtable