[build-script] Remove LLDB_DOTEST_CC_OPTS.

This variable is set but never used. The right way to set the test
compiler is by setting the corresponding CMake variables. This is likely
a remnant of the Xcode project support.

(cherry picked from commit 9c690e3)

Author: JDevlieghere

utils/build-script-impl

@@ -2984,18 +2984,6 @@ for host in "${ALL_HOSTS[@]}"; do
                 lldb_executable="${lldb_build_dir}"/bin/lldb
                 results_dir="${lldb_build_dir}/test-results"
 
-                # Figure out which C/C++ compiler we should use for building test inferiors.
-                if [[ "${LLDB_TEST_CC}" == "host-toolchain" ]]; then
-                    # Use the host toolchain: i.e. the toolchain specified by HOST_CC
-                    LLDB_DOTEST_CC_OPTS="-C ${HOST_CC}"
-                elif [[ -n "${LLDB_TEST_CC}" ]]; then
-                    # Use exactly the compiler path specified by the user.
-                    LLDB_DOTEST_CC_OPTS="-C ${LLDB_TEST_CC}"
-                else
-                    # Use the clang that was just built in the tree.
-                    LLDB_DOTEST_CC_OPTS="-C $(build_directory $LOCAL_HOST llvm)"/bin/clang
-                fi
-
                 # Options to find the just-built libddispatch and Foundation.
                 if [[ "$(uname -s)" == "Darwin" || "${SKIP_BUILD_FOUNDATION}" ]] ; then
                     DOTEST_EXTRA=""