Force CMake version 3.21.0+ for the FFMPEG extension

Issue: google/ExoPlayer#9933
#minor-release
PiperOrigin-RevId: 434449816

Author: AquilesCanta

RELEASENOTES.md

@@ -39,6 +39,10 @@
         `DEFAULT_TRACK_SELECTOR_PARAMETERS` constants. Use
         `getDefaultTrackSelectorParameters(Context)` instead when possible, and
         `DEFAULT_TRACK_SELECTOR_PARAMETERS_WITHOUT_CONTEXT` otherwise.
+    *   FFmpeg extension:
+        *   Update CMake version to `3.21.0+` to avoid a CMake bug causing
+            AndroidStudio's gradle sync to fail
+            ([#9933](https://github.com/google/ExoPlayer/issues/9933)).
 
 ### 1.0.0-alpha03 (2022-03-14)
 

libraries/decoder_ffmpeg/build.gradle

@@ -17,7 +17,8 @@ apply from: "$gradle.ext.androidxMediaSettingsDir/common_library_config.gradle"
 // failures if ffmpeg hasn't been built according to the README instructions.
 if (project.file('src/main/jni/ffmpeg').exists()) {
     android.externalNativeBuild.cmake.path = 'src/main/jni/CMakeLists.txt'
-    android.externalNativeBuild.cmake.version = '3.7.1+'
+    // Should match cmake_minimum_required.
+    android.externalNativeBuild.cmake.version = '3.21.0+'
 }
 
 dependencies {

libraries/decoder_ffmpeg/src/main/jni/CMakeLists.txt

@@ -14,7 +14,7 @@
 # limitations under the License.
 #
 
-cmake_minimum_required(VERSION 3.7.1 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.21.0 FATAL_ERROR)
 
 # Enable C++11 features.
 set(CMAKE_CXX_STANDARD 11)