Revert "Add -fdebug-compilation-dir option"

Revert submission 1461902-debug-compilation-dir

Reason for revert: "-Xclang" isn't being uniformly respected everywhere. For example, in ".S" compilations, when I pass `-Xclang -fdebug-compilation-dir=.", the assembler seems to be ignoring it and then inserting the `pwd` into the command, however when I pass "-fdebug-compilation-dir=.", it strips out the path to the current working directory.
This indicates that we need to update re-client's input processor so that we can pass -fdebug-compilation-dir=. without "-Xclang" and then remove `PWD` setting.
I'll followup with a patch to add -fdebug-compilation-dir.

Reverted Changes:
Ib0f271e55:Add -fdebug-compilation-dir option
Ifa0592af5:Remove env-var-allowlist

Change-Id: I12fa0bf2fb4975ac3d1bffaf1358331548abc339

cc/builder.go

@@ -44,14 +44,14 @@ var (
 		blueprint.RuleParams{
 			Depfile:     "${out}.d",
 			Deps:        blueprint.DepsGCC,
-			Command:     "${config.CcWrapper}$ccCmd -c $cFlags -MD -MF ${out}.d -o $out $in",
+			Command:     "$relPwd ${config.CcWrapper}$ccCmd -c $cFlags -MD -MF ${out}.d -o $out $in",
 			CommandDeps: []string{"$ccCmd"},
 		},
 		"ccCmd", "cFlags")
 
 	ccNoDeps = pctx.AndroidStaticRule("ccNoDeps",
 		blueprint.RuleParams{
-			Command:     "$ccCmd -c $cFlags -o $out $in",
+			Command:     "$relPwd $ccCmd -c $cFlags -o $out $in",
 			CommandDeps: []string{"$ccCmd"},
 		},
 		"ccCmd", "cFlags")
@@ -220,7 +220,7 @@ var (
 			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)