Replace *Escape with *EscapeList

Follow the change to blueprint to make *Escape take and return a string
and add *EscapeList that take and return slices of strings.  Fix up
a few places that were unnecessarily converting a string to a slice
and back to a string.

Test: m nothing
Change-Id: I3fa87de175522205f36544ef76aa2f04aef1b936
diff --git a/cc/linker.go b/cc/linker.go
index 25aedd0..9d4a0e8 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -392,7 +392,7 @@
 
 	CheckBadLinkerFlags(ctx, "ldflags", linker.Properties.Ldflags)
 
-	flags.LdFlags = append(flags.LdFlags, proptools.NinjaAndShellEscape(linker.Properties.Ldflags)...)
+	flags.LdFlags = append(flags.LdFlags, proptools.NinjaAndShellEscapeList(linker.Properties.Ldflags)...)
 
 	if ctx.Host() {
 		rpath_prefix := `\$$ORIGIN/`