[v2.3.14] add a new cli option to enable "regcomp(cflags|=REG_NEWLINE)"

Related subcommands

• expect -re PATTERN
• ~expect -glob PATTERN~
• interact -re PATTERN
• interact -subst PATTERN::REPLACE

New option name?

• ~-REG_NEWLINE~
• -anchor-newline | -anchor

Implementation

• With -anchor-newline, is it good idea to convert \r+\n to \n before calling regexec()?
  • Don't bother!