Revert "Reland "Bump the global default C standard to gnu23.""

This reverts commit cfb576268173f49f711b0bedab05fe879c0a1621.

Reason for revert: DroidMonitor: Potential culprit for http://b/397694474 - verifying through ABTD before revert submission. Please note that this is part of our standard investigation process and does not necessarily mean your CL will be reverted.

Change-Id: Ib84fb17a23726e7081494766927b52e0f04997ab
diff --git a/cc/cc_test.go b/cc/cc_test.go
index 2be4e48..98af7b6 100644
--- a/cc/cc_test.go
+++ b/cc/cc_test.go
@@ -2689,7 +2689,7 @@
 	cppOnly := []string{"-fPIC", "${config.CommonGlobalCppflags}", "${config.DeviceGlobalCppflags}", "${config.ArmCppflags}"}
 
 	cflags := []string{"-Werror", "-std=candcpp"}
-	cstd := []string{"-std=gnu23", "-std=conly"}
+	cstd := []string{"-std=gnu17", "-std=conly"}
 	cppstd := []string{"-std=gnu++20", "-std=cpp", "-fno-rtti"}
 
 	lastNDKFlags := []string{