Use multiple jobs when possible

.github/workflows/temp.yml

@@ -116,7 +116,7 @@ jobs:
          git clone --depth=1 https://github.com/torvalds/linux.git linux
          cd linux
          make defconfig
-         bear -- make LLVM=-18
+         bear -- make LLVM=-18 -j $(nproc)
 
      - name: Clone vast benchmark directory
        uses: actions/checkout@v4
@@ -133,7 +133,7 @@ jobs:
          vast-front # TODO: Determine if this is the correct path to vast-front
          linux/compile_commands.json
          vast_linux_kernel_mlir_with_unsup/
-         --num_processes=8
+         --num_processes=$(nproc)
          --vast_option="-xc"
          --vast_option="-vast-emit-mlir=${{ matrix.vast-target }}"
          > vast_linux_kernel_times_hl_with_unsup.tsv