Fix comma bug

[Devon7]

Fix bug where erroneous commas in #A, #C or #S literals create bogus values which cause errors (possibly much) later.

Before: #C(0 ,1) >> Error: The value (#:|`,| . 1) is not of the expected type REAL.

After: #C(0 ,1) >> Error: … Comma inside complex literal

Best compared sans whitespace, i.e., https://github.com/Clozure/ccl/pull/407/files?w=1

[Oops, accidentally deleted identical pull request #392]