Rather than using the (munged) output of "gcc -E" we now capture
precisely the output we expect from every test case. This allows us to
stay immune from strange output from gcc (unpredictable whitespace
output---aprticularly with different gcc versions).
This will also allow us to write tests that capture expected error
messages from the preprocessor as well.
Remove blank lines from output files before comparing.
Recently I'm seeing cases where "gcc -E" mysteriously omits blank
lines, (even though it prints the blank lines in other very similar
cases). Rather than trying to decipher and imitate this, just get rid
of the blank lines.
This approach with sed to kill the lines before the diff is better
than "diff -B" since when there is an actual difference, the presence
of blank lines won't make the diff harder to read.
Validate desired test cases by ensuring the output of glcpp matches
the output of the gcc preprocessor, (ignoring any lines of the gcc
output beginning with '#').
Only one test case so far with a trivial #define.