engine: common: soundlib: libmpg: backport fix for CVE-2017-12839.

Original patch: https://www.mpg123.de/cgi-bin/scm/mpg123/trunk/src/libmpg123/getbits.h?view=patch&r1=2024&r2=4323
Same as: 8a5e21a2a2

engine/common/soundlib/libmpg/getbits.h

@@ -47,6 +47,10 @@ static uint getbits( mpg123_handle_t *fr, int number_of_bits )
 {
 	ulong	rval;
 
+	if( (long)(fr->wordpointer-fr->bsbuf)*8
+	    + fr->bitindex+number_of_bits > (long)fr->framesize*8 )
+		return 0;
+
 	rval = fr->wordpointer[0];
 	rval <<= 8;
 	rval |= fr->wordpointer[1];