CI: macOS w/ AppleClang

Change macOS CI to use the native system compiler,
AppleClang, for C/C++ and only gfortran for the Fortran part.

Try to unbreak macOS CI failures.

.github/workflows/dependencies/dependencies_mac.sh

@@ -8,7 +8,7 @@
 set -eu -o pipefail
 
 brew update
-brew reinstall gcc || true
+brew install gfortran || true
 brew install libomp || true
 brew install open-mpi || true
 brew install ccache || true

.github/workflows/macos.yml

@@ -3,7 +3,7 @@ name: macos
 on: [push, pull_request]
 
 env:
-  CXXFLAGS: "-Werror -Wshadow -Woverloaded-virtual -Wextra-semi -Wunreachable-code -fno-operator-names"
+  CXXFLAGS: "-Werror -Wshadow -Woverloaded-virtual -Wextra-semi -Wunreachable-code -fno-operator-names -Wno-pass-failed"
 
 jobs:
   # Build all tutorials
@@ -16,8 +16,6 @@ jobs:
       run: .github/workflows/dependencies/dependencies_mac.sh
     - name: Build & Install
       run: |
-        export LIBRARY_PATH=/usr/local/opt/gcc/lib/gcc/current
-
         cd ExampleCodes
         cmake -S . -B build             \
             -DBUILD_SHARED_LIBS=ON      \
@@ -28,8 +26,6 @@ jobs:
             -DAMReX_FORTRAN_INTERFACES=ON \
             -DAMReX_EB=ON                 \
             -DAMReX_PARTICLES=ON        \
-            -DCMAKE_C_COMPILER=$(which gcc)              \
-            -DCMAKE_CXX_COMPILER=$(which g++)            \
             -DCMAKE_Fortran_COMPILER=$(which gfortran)   \
             -DCMAKE_CXX_COMPILER_LAUNCHER=$(which ccache)
         cmake --build build --parallel 2
@@ -42,8 +38,6 @@ jobs:
             -DAMReX_FORTRAN_INTERFACES=ON \
             -DAMReX_EB=ON                 \
             -DAMReX_PARTICLES=ON        \
-            -DCMAKE_C_COMPILER=$(which gcc)              \
-            -DCMAKE_CXX_COMPILER=$(which g++)            \
             -DCMAKE_Fortran_COMPILER=$(which gfortran)   \
             -DCMAKE_CXX_COMPILER_LAUNCHER=$(which ccache)
         cmake --build build --parallel 2