fix for lcov test for mips little endian

[reed kotler]

Change xfail condition so that it works properly for little endian Mips.

Mips was added to the list of xfail targers but only big endian mips 
should have been added.

Per the suggest of Daniel Sanders, this fixes the issues and I have 
checked it on our
little endian Mips machines.

I need approval to check into this part of llvm.
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diff --git a/test/tools/llvm-cov/llvm-cov.test b/test/tools/llvm-cov/llvm-cov.test
index afd657b..19d3e5d 100644
--- a/test/tools/llvm-cov/llvm-cov.test
+++ b/test/tools/llvm-cov/llvm-cov.test
@@ -91,4 +91,4 @@ RUN: not llvm-cov test.c -gcda=test_file_checksum_fail.gcda
 # Bad function checksum on gcda
 RUN: not llvm-cov test.c -gcda=test_func_checksum_fail.gcda
 
-XFAIL: powerpc64, s390x, mips, sparc
+XFAIL: powerpc64, s390x, mips-, mips64-, sparc