[SCons] Make Fortran compiler and options consistent

In some cases, the setting of "SHF90" (the compiler to use for
compiling shared objects from F90 code) does not inherit the setting
of "F90" (the compiler to use for compiling normal objects from F90
code). This changes these two to be consistent, as well as the
corresponding variables for other Fortran compilers.

SConstruct

@@ -1154,6 +1154,10 @@ else: # env['system_sundials'] == 'n'
     env['sundials_version'] = '5.3'
     env['has_sundials_lapack'] = int(env['use_lapack'])
 
+def set_fortran(pattern, value):
+    # Set compiler / flags for all Fortran versions to be the same
+    for version in ("FORTRAN", "F77", "F90", "F95", "F03", "F08"):
+        env[pattern.format(version)] = value
 
 # Try to find a working Fortran compiler:
 def check_fortran(compiler, expected=False):
@@ -1163,7 +1167,7 @@ program main
 end program main
     '''
     if which(compiler):
-        env['F77'] = env['F90'] = env['F95'] = env['F03'] = env['FORTRAN'] = compiler
+        set_fortran("{}", compiler)
         success, output = conf.TryRun(hello_world, '.f90')
         if success and 'Hello, world!' in output:
             return True
@@ -1177,7 +1181,7 @@ end program main
 
     return False
 
-env['F77FLAGS'] = env['F90FLAGS'] = env['F95FLAGS'] = env['F03FLAGS'] = env['FORTRANFLAGS']
+set_fortran("{}FLAGS", env["FORTRANFLAGS"])
 
 if env['f90_interface'] in ('y','default'):
     foundF90 = False
@@ -1210,8 +1214,8 @@ elif 'g95' in env['FORTRAN']:
 elif 'ifort' in env['FORTRAN']:
     env['FORTRANMODDIRPREFIX'] = '-module '
 
-env['F77'] = env['F90'] = env['F95'] = env['F03'] = env['FORTRAN']
-
+set_fortran("{}", env["FORTRAN"])
+set_fortran("SH{}", env["FORTRAN"])
 env['FORTRANMODDIR'] = '${TARGET.dir}'
 
 env = conf.Finish()