Reland "Enable Fortran testsuite/language when TEST_SUITE_SUBDIRS=For…

…tran is passed"

This relands 8c18b14 with a small fix to
use the IN_LIST operator.

Differential Revision: https://reviews.llvm.org/D139633

CMakeLists.txt

@@ -2,10 +2,16 @@ cmake_minimum_required(VERSION 3.13.4)
 
 include(CheckSymbolExists)
 
-option(TEST_SUITE_FORTRAN "Enable Fortran test suite" OFF)
 
 project(test-suite C CXX)
 
+if("Fortran" IN_LIST TEST_SUITE_SUBDIRS)
+  set(TEST_SUITE_FORTRAN_default ON)
+else()
+  set(TEST_SUITE_FORTRAN_default OFF)
+endif()
+option(TEST_SUITE_FORTRAN "Enable Fortran test suite" ${TEST_SUITE_FORTRAN_default})
+
 if(TEST_SUITE_FORTRAN)
   enable_language(Fortran)
 endif()

Fortran/UnitTests/fcvs21_f95/CMakeLists.txt

@@ -33,6 +33,8 @@
 # explicit acknowledgement of what has been changed. Please
 # amend README file if you modify the tests.
 
+include(CheckFortranCompilerFlag)
+
 # clean-up fort.* files otherwise one of the tests will fail
 llvm_test_prepare(rm -f %S/fort.*)