stagefright: Fix metadata/message conversion issues

 * Remove duplication of code between ExtendedCodec and FFMPEGSoftCodec,
   just call into ExtendedCodec and properly ifdef QCOM-only parts.
 * Fix CSD not being converted when AV_ENHANCEMENTS wasn't set- this
   was breaking the software video codecs on Hammerhead.

Change-Id: I9cd4316ce19b15baabf12b78b992498ce48e2697
libstagefright: Fix QCOM_BSP_LEGACY cflags

Change-Id: I432541f4923a42b1fafcff8fcd886c81c94ba3be
Fix compile error after I9cd4316ce19b15baabf12b78b992498ce48e2697

frameworks/av/media/libstagefright/ExtendedCodec.cpp:1187:1: error:
expected '}' at end of input

Change-Id: I7d75e69160f794b177f4235f4a6bb5a188dc0d08