Fix strings passed to die and add "xiph" to ogg/vorbis functions.
Fix strings passed to die and add "xiph" to ogg/vorbis functions.

1. It does not help to put $1 in a msg when trying to let the user know that
a positional parameter was empty.
2. The "xiph" bit is for the sake of differentiating the xipg related
functions from the libvpx functions that will be added in the next commit.
3. Wrapped xiph commands in block controlled by disable_xiph_builds flag.

Change-Id: Ifed4bc890e42ed4600e2260e1a43c08df3a8a323

Acidburn0zzz/webm.webmdshow,altogother/webm.webmdshow,Acidburn0zzz/webm.webmdshow,kalli123/webm.webmdshow,zofuthan/webmdshow,kalli123/webm.webmdshow,matanbs/webm.webmdshow,Maria1099/webm.webmdshow,iniwf/webm.webmdshow,gshORTON/webm.webmdshow,webmproject/webmdshow,matanbs/webm.webmdshow,abwiz0086/webm.webmdshow,gshORTON/webm.webmdshow,brion/webmdshow,brion/webmdshow,matanbs/webm.webmdshow,kleopatra999/webm.webmdshow,Acidburn0zzz/webm.webmdshow,kalli123/webm.webmdshow,iniwf/webm.webmdshow,webmproject/webmdshow,webmproject/webmdshow,kleopatra999/webm.webmdshow,abwiz0086/webm.webmdshow,abwiz0086/webm.webmdshow,matanbs/webm.webmdshow,kim42083/webm.webmdshow,brion/webmdshow,ericmckean/webm.webmdshow,ericmckean/webm.webmdshow,Maria1099/webm.webmdshow,brion/webmdshow,iniwf/webm.webmdshow,brion/webmdshow,webmproject/webmdshow,altogother/webm.webmdshow,kleopatra999/webm.webmdshow,kim42083/webm.webmdshow,iniwf/webm.webmdshow,Maria1099/webm.webmdshow,zofuthan/webmdshow,kalli123/webm.webmdshow,Acidburn0zzz/webm.webmdshow,ericmckean/webm.webmdshow,zofuthan/webmdshow,gshORTON/webm.webmdshow,kleopatra999/webm.webmdshow,ericmckean/webm.webmdshow,Maria1099/webm.webmdshow,altogother/webm.webmdshow,abwiz0086/webm.webmdshow,altogother/webm.webmdshow,gshORTON/webm.webmdshow,zofuthan/webmdshow,kim42083/webm.webmdshow,kim42083/webm.webmdshow