Manually escape BuildNumberFromFile

Change ctx.Config().BuildNumberFromFile() to be unescaped, and then
escape it manually where necessary.  This will allow passing
ctx.Config().BuildNumberFromFile() to RuleBuilder, which will handle
the necessary escaping.

Test: no change to out/soong/build.ninja
Change-Id: I5329ab2ba70ccea49958864488aa81794a7e4b56

cc/linker.go

@@ -483,7 +483,7 @@ func (linker *baseLinker) injectVersionSymbol(ctx ModuleContext, in android.Path
 		Input:       in,
 		Output:      out,
 		Args: map[string]string{
-			"buildNumberFromFile": ctx.Config().BuildNumberFromFile(),
+			"buildNumberFromFile": proptools.NinjaEscape(ctx.Config().BuildNumberFromFile()),
 		},
 	})
 }