Convert some Args index-based iteration to range-style iteration.

This is better for a number of reasons.  Mostly style, but also:

1) Signed-unsigned comparison warnings disappear since there is
   no loop index.
2) Iterating with the range-for style gives you back an entry
   that has more than just a const char*, so it's more efficient
   and more useful.
3) Makes code safter since the type system enforces that it's
   impossible to index out of bounds.

llvm-svn: 283413

lldb/source/Host/linux/ProcessLauncherLinux.cpp

@@ -31,10 +31,8 @@ static void FixupEnvironment(Args &env) {
   // path to /system/bin. It is required because the default path used by
   // execve() is wrong on android.
   static const char *path = "PATH=";
-  static const int path_len = ::strlen(path);
-  for (size_t i = 0; i < env.GetArgumentCount(); ++i) {
-    const char *arg = env.GetArgumentAtIndex(i);
-    if (::strncmp(path, arg, path_len) == 0)
+  for (auto &entry : entries) {
+    if (entry.ref.startswith(path))
       return;
   }
   env.AppendArgument(llvm::StringRef("PATH=/system/bin"));