extensions/av1: use -O2 for release builds

+ force arm (over thumb) mode for 32-bit builds

-O2 improves performance ~30-40% over the default -Oz depending on the
resolution; this is similar to what is done for vp9 which uses -O3.

PiperOrigin-RevId: 290318121

extensions/av1/src/main/jni/CMakeLists.txt

@@ -11,9 +11,15 @@ project(libgav1JNI C CXX)
 # armeabi-v7a build. This flag enables it.
 if(${ANDROID_ABI} MATCHES "armeabi-v7a")
     add_compile_options("-mfpu=neon")
+    add_compile_options("-marm")
     add_compile_options("-fPIC")
 endif()
 
+string(TOLOWER "${CMAKE_BUILD_TYPE}" build_type)
+if(build_type MATCHES "^rel")
+    add_compile_options("-O2")
+endif()
+
 set(libgav1_jni_root "${CMAKE_CURRENT_SOURCE_DIR}")
 set(libgav1_jni_build "${CMAKE_BINARY_DIR}")
 set(libgav1_jni_output_directory