Add -fdebug-compilation-dir option

The main use of this flag is to be to make both the debug info
and the build command line be independent of the compilation dir.
See: https://reviews.llvm.org/D63387 & https://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html

Removed -fdebug-prefix-map and PWD variable being set in the compile
command line - these were workarounds we originally did to ensure that
the compile output is independent of the working directory and are no
longer needed now that we have -fdebug-compilation-dir.

Test: Ran "m
out/target/product/crosshatch/obj/SHARED_LIBRARIES/libexif.vendor_intermediates/same_vndk_variants.timestamp"
which fails on an RBE hardened stack without this change and passes with
this change.

Bug: b/169266636
Change-Id: Ib0f271e55f6cf0c89a30e65d3a0b25fe3f3a8f48
diff --git a/cc/builder.go b/cc/builder.go
index 81c09b1..8c8aa17 100644
--- a/cc/builder.go
+++ b/cc/builder.go
@@ -44,14 +44,14 @@
 		blueprint.RuleParams{
 			Depfile:     "${out}.d",
 			Deps:        blueprint.DepsGCC,
-			Command:     "$relPwd ${config.CcWrapper}$ccCmd -c $cFlags -MD -MF ${out}.d -o $out $in",
+			Command:     "${config.CcWrapper}$ccCmd -c $cFlags -MD -MF ${out}.d -o $out $in",
 			CommandDeps: []string{"$ccCmd"},
 		},
 		"ccCmd", "cFlags")
 
 	ccNoDeps = pctx.AndroidStaticRule("ccNoDeps",
 		blueprint.RuleParams{
-			Command:     "$relPwd $ccCmd -c $cFlags -o $out $in",
+			Command:     "$ccCmd -c $cFlags -o $out $in",
 			CommandDeps: []string{"$ccCmd"},
 		},
 		"ccCmd", "cFlags")
@@ -220,7 +220,7 @@
 			Labels:       map[string]string{"type": "abi-dump", "tool": "header-abi-dumper"},
 			ExecStrategy: "${config.REAbiDumperExecStrategy}",
 			Platform: map[string]string{
-				remoteexec.PoolKey:      "${config.RECXXPool}",
+				remoteexec.PoolKey: "${config.RECXXPool}",
 			},
 		}, []string{"cFlags", "exportDirs"}, nil)