This allows ${%Y:L:gmtime=${mtime}} instead of the indirect
${%Y:L:${:Ugmtime=${mtime}}}.
The direct form also prevents any ':' from the nested expression to be
interpreted as a separator, which doesn't matter for the ':gmtime' and
':localtime' modifiers but will prove useful for other modifiers that
follow the same pattern.
The comparison operator had accidentally been '!=' instead of '=='.
While here, proofread the documentation and add references for where the
32-bit time_t is defined on Linux and FreeBSD.
It's easier to have both the expressions and the expected values in a
single file. This also allows for flexible handling of multiple
acceptable outputs, in this case for 32-bit time_t.
The test names have been derived from the current manual page.
All these tests are dummies right now, and the code from the existing
tests will be moved into the new tests step by step.
This is done to prevent modmisc, escape, varmod-edge and varmisc from
growing without any bounds, and to reduce the side-effects of one test
to the others.
rillig