[Bug d/94305] New: libphobos: Add configure flag to build phobos in non-release mode

[ibuclaw at gdcproject dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94305

            Bug ID: 94305
           Summary: libphobos: Add configure flag to build phobos in
                    non-release mode
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: ibuclaw at gdcproject dot org
  Target Milestone: ---

Currently, libphobos is always built in non-release mode, which means all
asserts, contracts and invariants are compiled in.

For speed, `-frelease' should be the default, but allow this to be overridden
for testing purposes.  Maybe re-using --enable-checking?