dealii: add GMSH, add CMAKE_FIND_APPBUNDLE to CMakePackage (#6723)

* dealii: add GMSH dependency

* CMakePackage: add CMAKE_FIND_APPBUNDLE to prevent picking up binaries from /Applications

lib/spack/spack/build_systems/cmake.py

@@ -140,7 +140,10 @@ def _std_args(pkg):
         ]
 
         if platform.mac_ver()[0]:
-            args.append('-DCMAKE_FIND_FRAMEWORK:STRING=LAST')
+            args.extend([
+                '-DCMAKE_FIND_FRAMEWORK:STRING=LAST',
+                '-DCMAKE_FIND_APPBUNDLE:STRING=LAST'
+            ])
 
         # Set up CMake rpath
         args.append('-DCMAKE_INSTALL_RPATH_USE_LINK_PATH:BOOL=FALSE')