Make DWARF v5 the default debug information format.

This makes DWARF v5 the default debug information format for C/C++
programs in the Platform that are compiled with LLVM.

Test: Testing in progress.
Bug: b/182004844
Change-Id: I9aa6a3ca05ac0fdfa54f556c2e20ffd818b25420
diff --git a/cc/config/global.go b/cc/config/global.go
index ed18300..3790676 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -46,6 +46,7 @@
 
 		"-O2",
 		"-g",
+		"-fdebug-default-version=5",
 		"-fdebug-info-for-profiling",
 
 		"-fno-strict-aliasing",