ffmpeg/ffmpegx: disable lzma and alsa as ffmpeg has no dependency on xz or alsa

ffmpeg[x] will auto-detect lzma (from xz, built by vfs.libarchive) and alsa,
however these packages are built after ffmpeg so that when ffmpeg is rebuilt
these libraries are now found, resulting in a different binary than when clean.

Solution: don't auto-detect.

packages/addons/addon-depends/ffmpegx/package.mk

@@ -149,6 +149,8 @@ configure_target() {
     \
     `#General options` \
     --enable-avresample \
+    --disable-lzma \
+    --disable-alsa \
     \
     `#Toolchain options` \
     --arch="$TARGET_ARCH" \

packages/multimedia/ffmpeg/package.mk

@@ -179,6 +179,8 @@ configure_target() {
               --enable-filters \
               --disable-avisynth \
               --enable-bzlib \
+              --disable-lzma \
+              --disable-alsa \
               --disable-frei0r \
               --disable-libopencore-amrnb \
               --disable-libopencore-amrwb \