Update linux.yml

Author: houjun

.github/workflows/linux.yml

@@ -98,6 +98,7 @@ jobs:
           ctest
 
           # Compile PDC
+          mkdir $PDC_DIR
           cd $PDC_DIR
           git checkout develop
           cmake ../ -DBUILD_MPI_TESTING=ON -DBUILD_SHARED_LIBS=ON -DBUILD_TESTING=ON -DCMAKE_INSTALL_PREFIX=$PDC_DIR -DPDC_ENABLE_MPI=ON -DMERCURY_DIR=$MERCURY_DIR -DCMAKE_C_COMPILER=mpicc