Fix TAP checks when current directory name contains spaces

Add some quotes in the makefile snippet that creates the temporary
installation, so that it can handle spaces in the directory name and
possibly some other oddities.
Fix configure check for %z printf support after INT64_MODIFIER changes.

The PGAC_FUNC_SNPRINTF_SIZE_T_SUPPORT test was broken by
ce486056ecd28050. Among others it made the UINT64_FORMAT macro to be
defined in c.h, instead of directly being defined by configure.

This lead to the replacement printf being used on all platforms for a
while. Which seems to work, because this was only used due to
different profiles ;)

Fix by relying on INT64_MODIFIER instead.