Attemp to fix build bot after r270987

It was: "Recommit 270977 - [llvm-mc] - Teach llvm-mc to generate zlib styled compression sections."

Fix:
since test requires no zlib available and r270987 changed the 
compression flag for llvm-mc to mandatory specify the compression style,
then just add 2 available styles to this test.

llvm-svn: 270992