Add checks to HW codecs to ensure unsupported features are not used.

Add checks to ensure encoder is not used below API level 19. Removes
global @TargetApi from MediaCodecUtils since it is also used by the
decoder. Ensures that texture mode is never enabled below API level 18.

Bug: webrtc:9821
Change-Id: I2ca1014bf8995719c970eb1449b0acbf7b3c883e
Reviewed-on: https://webrtc-review.googlesource.com/c/103701
Reviewed-by: Paulina Hensman <phensman@webrtc.org>
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24990}

sdk/android/api/org/webrtc/HardwareVideoEncoderFactory.java

@@ -64,6 +64,11 @@ public class HardwareVideoEncoderFactory implements VideoEncoderFactory {
   @Nullable
   @Override
   public VideoEncoder createEncoder(VideoCodecInfo input) {
+    // HW encoding is not supported below Android Kitkat.
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
+      return null;
+    }
+
     VideoCodecType type = VideoCodecType.valueOf(input.name);
     MediaCodecInfo info = findCodecForType(type);
 
@@ -100,6 +105,11 @@ public class HardwareVideoEncoderFactory implements VideoEncoderFactory {
 
   @Override
   public VideoCodecInfo[] getSupportedCodecs() {
+    // HW encoding is not supported below Android Kitkat.
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
+      return new VideoCodecInfo[0];
+    }
+
     List<VideoCodecInfo> supportedCodecInfos = new ArrayList<VideoCodecInfo>();
     // Generate a list of supported codecs in order of preference:
     // VP8, VP9, H264 (high profile), and H264 (baseline profile).