The Pelles C compiler does not support ASM, and the `poasm` assembler
uses a distinct syntax. Add a dedicated language as we do for similar
cases from other vendors. Leave documentation commented out for now
because the PellesC toolchain support in general is not yet documented.
Fixes: #27758
Issue: #21536
Co-authored-by: Serguei E. Leontiev <leo@sai.msu.ru>
Try to be a bit more consistent about:
- Placing angle brackets around text which serves as a placeholder
rather than being literal.
- Using curly brackets rather than angle brackets to denote groups where
one of the options is required.
- Describing optional list arguments like `<x>...` rather than
`[<x>...]`. (Instances of lists not associated with keywords are
intentionally left as-is, however.)
Also, teach our CMake lexer to understand curly braces used as above
(prior uses were only in parsed literals without syntax highlighting),
and to highlight them (and remaining uses of angle braces) as the type
Punctuation rather than the type Operator, for consistency with square
braces.
