[Fortran] Flexible matching for long character constant in FCVS FM905

[rovka]

Summary

FM905 uses list-directed output for printing a long character constant.
By default, flang splits the constant when it reaches a line length of
80, whereas gfortran leaves it all on one line.

I couldn't find a clear way to tell flang to never introduce newlines,
nor a way to force a line length for gfortran. However, flang's line
length can be controlled via an environment variable called
FORT_FMT_RECL, so this patch updates the reference output to leave the
line unsplit (as gfortran would print it), and to set FORT_FMT_RECL to
1000 unless otherwise defined in the environment (which will effectively
cause flang to dump the whole constant on one line).

Fortran/UnitTests/fcvs21_f95/FM905.reference_output

-3 15.25 HELLO T
        -3  15.25  HELLO  T
      8    INSPECT
                  COMPUTED= 
  5 O'CLOCK
                  CORRECT=  
        5 O'CLOCK
      9    INSPECT
                  COMPUTED= 
- SHORTTHIS IS A LONGER CHARACTER STRING1234567890123456789012345678901234567890
- 12345678901234567890123456789012          
+ SHORTTHIS IS A LONGER CHARACTER STRING123456789012345678901234567890123456789012345678901234567890123456789012          
                  CORRECT=  
  SHORT  THIS IS A LONGER CHARACTER STRING 123456789012345678901234567890123456789
  012345678901234567890123456789012
     10    INSPECT
                  COMPUTED= 
  5 5 5 5 5
                  CORRECT=  
        5  5  5  5  5  OR  5*5

Fortran/UnitTests/fcvs21_f95/lit.local.cfg

 config.traditional_output = True
 config.single_source = True
 
 # Flang uses NO_STOP_MESSAGE to control the output of the STOP statement. If
 # it is present in the environment, we should forward it to the tests, otherwise
 # they might choke on warnings about signaling INEXACT exceptions.
 if 'NO_STOP_MESSAGE' in os.environ:
   config.environment['NO_STOP_MESSAGE'] = os.environ['NO_STOP_MESSAGE']
+
+# Flang uses FORT_FMT_RECL to control the length of a line for list-directed
+# output. FM905 needs a large enough value for this (values larger than about
+# 150 should work). We either forward the value that we find in the environment,
+# or set a default of 1000 to make sure the test passes.
+if 'FORT_FMT_RECL' in os.environ:
+  config.environment['FORT_FMT_RECL'] = os.environ['FORT_FMT_RECL']
+else:
+  config.environment['FORT_FMT_RECL'] = "1000"