Remove unnecessary TEXTBC_LIBS makefile definition.

Jan correctly pointed out that this makefie definition was redundant
since -lLLVMNaClBitTestUtils was already defined in LLVM_LIBS_LIST.
Removing the definition and simplifying makefile.

BUG=None
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1211593003.
1 file changed