openmolcas: fix build on aarch64. (#17923)

var/spack/repos/builtin/packages/openmolcas/CMakeLists.txt.patch

+--- spack-src/CMakeLists.txt.bak	2019-11-12 20:59:54.000000000 +0900
++++ spack-src/CMakeLists.txt	2020-08-07 16:37:11.600570176 +0900
+@@ -559,7 +559,8 @@
+         if ((${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86") OR
+             (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "i686"))
+                 set (PLATFORM "LINUX")
+-        elseif (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64")
++	elseif ((${CMAKE_SYSTEM_PROCESSOR} STREQUAL "x86_64") OR
++                (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "aarch64"))
+                 set (PLATFORM "LINUX64")
+         elseif (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "ia64")
+                 set (PLATFORM "LINUX64_IA")

var/spack/repos/builtin/packages/openmolcas/package.py

@@ -23,6 +23,8 @@ class Openmolcas(CMakePackage):
     depends_on('py-pyparsing', type=('build', 'run'))
     depends_on('py-six', type=('build', 'run'))
 
+    patch('CMakeLists.txt.patch', when='target=aarch64:')
+
     def setup_build_environment(self, env):
         env.set('MOLCAS', self.prefix)