Define default RE2C_FLAGS

[petk]

The --no-generation-date flag is a common re2c flag used in all re2c invocations. This adds the 2nd optional argument to PHP_PROG_RE2C M4 macro in BC manner to set the default re2c command-line options and sets the default RE2C_FLAGS similarly on Windows.

• I'll recheck if everything works correctly and matches the php-src workflow, otherwise looks ok already.

[devnexen]

Makes sense, even though I m not a lexer expert :)

[petk]

Makes sense, even though I m not a lexer expert :)

This flag (--no-genearation-date) only adds the generated date in the top of the file's header comment. Nothing specific to functionality of the generated code here. Other flags are a bit more specific to each file individually otherwise.

[petk]

Rechecked and all seems to be working as expected, also that sed command seems to be working from my tests correctly across some exotic shells. Then I think this is ready for merge in the following days.

[petk]

I've only appended some CS and help text fixes here. Merge coming up then. This works ok for now. The -g flag is being fixed separately in #11928 because the entire check needs to be refactored a bit further. And it can be also improved on the way in the future as needed. For example, adding -W option when developing can still be done with manual override of the RE2C_FLAGS at the make step: make RE2C_FLAGS=-W and similar.