r178471 - Modifed debug-info-byval.cpp test to grep for .string or .asciz.

[Jyotsna Verma]

>Thanks. In general, if you see a testcase in the front end that looks at
>assembly you should split it into two testcases: one that tests the IR
>generated, and a separate test case in the back end that tests for the
>assembly/object file that is desired.
>
>In this case you definitely want to do that and turn it into one that emits
>object files and look at the output of llvm-dwarfdump.

I have split the debug-info-byval.cpp test into two tests, one for the front
end and one for the back end. They work fine for x86. However, Hexagon
doesn't have an integrated assembler at this point and therefore can't emit
the object file needed by llvm-dwarfdump. I suppose I will have to use the
assembly output just like the original test.
 
-Jyotsna