compiler_wrapper: disable unused-but-set warnings

This CL disables no-unused-but-set-variable warnings globally in the
compiler wrapper. A seperate CL will specifically reenable this warning
for platform2. This prevents breakage do to unised variables in
third_party.

BUG=None
TEST=None

Change-Id: I2ea44b6249715d3b036843b13d668d50b9b7669d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3150656
Tested-by: Ryan Beltran <ryanbeltran@chromium.org>
Auto-Submit: Ryan Beltran <ryanbeltran@chromium.org>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Commit-Queue: Manoj Gupta <manojgupta@chromium.org>
diff --git a/compiler_wrapper/cros_llvm_next_flags.go b/compiler_wrapper/cros_llvm_next_flags.go
index 0c8dc67..d2ae413 100644
--- a/compiler_wrapper/cros_llvm_next_flags.go
+++ b/compiler_wrapper/cros_llvm_next_flags.go
@@ -14,7 +14,7 @@
 
 // TODO: Enable test in config_test.go, once we have new llvm-next flags.
 var llvmNextFlags = []string{
-	"-Wl,-z,nostart-stop-gc",
+	"-Wno-unused-but-set-variable",
 }
 
 var llvmNextPostFlags = []string{}