Disable build of FFmpeg on iOS from toolchain since it cannot build

ENABLE_FFMPEG is anyway set to OFF on iOS.

Seems CMAKE_OSX_DEPLOYMENT_TARGET has to be set to minimum iOS 13 in
order for FFmpeg to build.

.github/workflows/ios.yml

@@ -37,7 +37,7 @@ jobs:
     - name: Build TeamTalk Library
       working-directory: ${{runner.workspace}}/TeamTalk5/Build
       run: |
-        make CMAKE_EXTRA="-DFEATURE_WEBRTC=OFF -DCMAKE_OSX_ARCHITECTURES=${{ matrix.cmakearch }} -DCMAKE_OSX_SYSROOT=${{ matrix.cmakesysroot }} -DCMAKE_INSTALL_PREFIX=${{runner.workspace}}/install-${{ matrix.cmakearch }}" BUILDDIR=build-${{ matrix.cmakearch }} ios-build
+        make CMAKE_EXTRA="-DFEATURE_WEBRTC=OFF -DTOOLCHAIN_FFMPEG=OFF -DCMAKE_OSX_ARCHITECTURES=${{ matrix.cmakearch }} -DCMAKE_OSX_SYSROOT=${{ matrix.cmakesysroot }} -DCMAKE_INSTALL_PREFIX=${{runner.workspace}}/install-${{ matrix.cmakearch }}" BUILDDIR=build-${{ matrix.cmakearch }} ios-build
 
     - name: Run CMake Install Target
       working-directory: ${{runner.workspace}}/TeamTalk5/Build/build-${{ matrix.cmakearch }}

Library/TeamTalkLib/build/ffmpeg/CMakeLists.txt

@@ -239,7 +239,12 @@ elseif (${CMAKE_SYSTEM_NAME} MATCHES "iOS")
     ExternalProject_Get_Property(gas-preprocessor SOURCE_DIR)
     set (GAS_DIR ${SOURCE_DIR})
 
-    set (FFMPEG_CFG_FLAGS --target-os=darwin --sysroot=${CMAKE_OSX_SYSROOT} --enable-pic --disable-doc --disable-programs --enable-cross-compile)
+    set (FFMPEG_CFG_FLAGS --target-os=darwin --sysroot=${CMAKE_OSX_SYSROOT}
+      --enable-pic
+      --enable-cross-compile
+      --disable-doc
+      --disable-programs
+      --disable-audiotoolbox)
 
     if ("armv7" STREQUAL "${CMAKE_OSX_ARCHITECTURES}")
       list (APPEND FFMPEG_CFG_FLAGS --arch=arm --cpu=cortex-a8)