[build-script-impl] Fix obvious typo, where we were using LLVM_BUILD_TYPE instead of CMARK_BUILD_TYPE to set cmark's CMAKE_BUILD_TYPE.

Author: gottesmm

utils/build-script-impl

@@ -1745,7 +1745,7 @@ for host in "${ALL_HOSTS[@]}"; do
             cmark)
                 cmake_options=(
                   "${cmake_options[@]}"
-                  -DCMAKE_BUILD_TYPE:STRING="${LLVM_BUILD_TYPE}"
+                  -DCMAKE_BUILD_TYPE:STRING="${CMARK_BUILD_TYPE}"
                   "${cmark_cmake_options[@]}"
                 )
                 skip_build=${SKIP_BUILD_CMARK}