meson: Fix support for empty darwin sysroot
The -isysroot options should only be added if the sysroot resolved to
a nonempty string. This matches the behavior in src/template/darwin
(also documented in installation.sgml).
Discussion: https://www.postgresql.org/message-id/flat/60765bf0-5027-4b23-9f78-4a365d28823f%40enterprisedb.com
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/c15631f0f596b2e6c4b03f24c03289d06d008783
Modified Files
--------------
meson.build | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)