Check input file extension is not wav

This is an usual error while using neteq_quality_test. This tool
does not support wav files as input. Adding a validation.

Bug: webrtc:10690
Change-Id: I18ed308d2f688106728df5df25e0a58c7170f411
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/139104
Commit-Queue: Pablo Barrera González <barrerap@webrtc.org>
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28141}

modules/audio_coding/neteq/tools/neteq_quality_test.cc

diff --git a/modules/audio_coding/neteq/tools/neteq_quality_test.cc b/modules/audio_coding/neteq/tools/neteq_quality_test.cc
index 54d8bbb..81305ef 100644
--- a/modules/audio_coding/neteq/tools/neteq_quality_test.cc
+++ b/modules/audio_coding/neteq/tools/neteq_quality_test.cc
@@ -38,8 +38,13 @@
 }
 
 // Common validator for file names.
-static bool ValidateFilename(const std::string& value, bool write) {
-  FILE* fid = write ? fopen(value.c_str(), "wb") : fopen(value.c_str(), "rb");
+static bool ValidateFilename(const std::string& value, bool is_output) {
+  if (!is_output) {
+    RTC_CHECK_NE(value.substr(value.find_last_of(".") + 1), "wav")
+        << "WAV file input is not supported";
+  }
+  FILE* fid =
+      is_output ? fopen(value.c_str(), "wb") : fopen(value.c_str(), "rb");
   if (fid == nullptr)
     return false;
   fclose(fid);