[libc++] Fix fuzzing unit tests with exceptions disabled.

We simply turn off the parts of the tests that require exceptions.

Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 29b2f64ddb8b7ab7ca7215e8701386b9c4da1865
diff --git a/fuzzing/fuzzing.cpp b/fuzzing/fuzzing.cpp
index 2849939..9f3601f 100644
--- a/fuzzing/fuzzing.cpp
+++ b/fuzzing/fuzzing.cpp
@@ -457,6 +457,7 @@
 {
     if (size > 0)
     {
+#ifndef _LIBCPP_NO_EXCEPTIONS
         try
         {
             std::string s((const char *)data, size);
@@ -464,6 +465,11 @@
             return std::regex_match(s, re) ? 1 : 0;
         }
         catch (std::regex_error &ex) {}
+#else
+      ((void)data);
+      ((void)size);
+      ((void)flag);
+#endif
     }
     return 0;
 }