fix the escaping, and expand the path escaping

.github/workflows/ubuntu.yml

@@ -130,14 +130,16 @@ jobs:
 
       - name: Build shared GC (${{ matrix.gc_name }})
         run: |
+          MMTK_BUILD_PATH=$(pwd)/../src/gc/mmtk/target/release
+
           mkdir ${{ matrix.shared_gc_dir }} &&
           gcc -shared \
             -I../src/include \
             -I../src \
             -I.ext/include/x86_64-linux \
             -Wl,--verbose,--compress-debug-sections=zlib \
-            -Wl,--rpath=$(pwd)/../src/gc/mmtk/target/release
-            -L$(pwd)/../src/gc/mmtk/target/release -lmmtk_ruby \
+            -Wl,--rpath=$(MMTK_BUILD_PATH) \
+            -L$(readlink -f $MMTK_BUILD_PATH) -lmmtk_ruby \
             -fstack-protector-strong \
             -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 \
             -O3 -fno-fast-math -ggdb3 -DBUILDING_SHARED_GC -fPIC \