gn build: Silence mismatched-new-delete warning in scudo C++ wrapper tests.

[pcc]

Summary

These tests are deliberately mismatching new and delete, so the warnings
are just noise.

[merge_guards_bot]

Unit tests: pass. 61074 tests passed, 0 failed and 728 were skipped.

clang-tidy: fail. Please fix clang-tidy findings.

clang-format: pass.

Build artifacts: diff.json, clang-tidy.txt, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

llvm/utils/gn/secondary/compiler-rt/lib/scudo/standalone/tests/BUILD.gn

+import("//llvm/utils/gn/build/toolchain/compiler.gni")
 import("//llvm/utils/unittest/unittest.gni")
 
 unittest("ScudoUnitTest") {
   configs += [ "//llvm/utils/gn/build:crt_code" ]
   deps = [
     "//compiler-rt/lib/scudo/standalone:sources",
   ]
   sources = [
deps = [
     "//compiler-rt/lib/scudo/standalone:c_wrapper_sources",
     "//compiler-rt/lib/scudo/standalone:cxx_wrapper_sources",
     "//compiler-rt/lib/scudo/standalone:sources",
   ]
   sources = [
     "scudo_unit_test_main.cpp",
     "wrappers_cpp_test.cpp",
   ]
+  if (is_clang) {
+    cflags = [ "-Wno-mismatched-new-delete" ]
+  }
   has_custom_main = true
 }