mail/courier: Update to 1.5.1
The update fixes build with devel/courier-unicode 2.4.0
While here modernize and cleanup port:
- Modernize RUN_DEPENDS syntax
- Convert to USES=localbase
- Retire Noop options RCCONF and PERIODIC
- Convert to option helpers where possible/convenient
- Configure script unconditionally checks for gnupg, but in wrong path. So, moved it as unconditional RUN_DEPENDS, using helper ENV var to point to correct executable
- Sort variable and values (intentionally keeping ASPELL and ISPELL near though)
- Removed redundant pre-everything echoing well known information
- Fixed sqwebmail extra patches names/paths
- Fixed sqwebmail extra patch generating code that failed to compile
PR: 290504, 285602