[Clang] Correctly set LD_LIBRARY_PATH in env.c

Before the environment variable would have a LD_LIBRARY_PATH= prefix
which means we would be setting the variable incorrectly. Setting it
incorrectly does not seem to break anything but might impact test
fidelity.

Author: boomanaiden154

clang/test/Driver/env.c

@@ -1,6 +1,6 @@
 // Some assertions in this test use Linux style (/) file paths.
 // UNSUPPORTED: system-windows
-// RUN: bash -c env | grep LD_LIBRARY_PATH | tr -d '\n' > %t.ld_library_path
+// RUN: bash -c env | grep LD_LIBRARY_PATH | sed -ne 's/^.*=//p' | tr -d '\n' > %t.ld_library_path
 // The PATH variable is heavily used when trying to find a linker.
 // RUN: env -i LC_ALL=C LD_LIBRARY_PATH="%{readfile:%t.ld_library_path}" CLANG_NO_DEFAULT_CONFIG=1 \
 // RUN:   %clang %s -### -o %t.o --target=i386-unknown-linux \