Fix -DNEDUG builds

 - assert() is macro which is defined as empty, while panic is always
   present. I added an explicit abort() after the macro to make sure the
   function never returns in case of wrong flags.

 - Fixed gcc build with -NDEBUG, -Os for ARM.
   * A few 'may be used uninitialized' messages
   * A few new missing support library functions where added in libminc.

Change-Id: I69fcda2cd3888390b7ddeff4c0cd849105ce86ff