build: update gnulib to latest; more *BSD and Solaris work-arounds

diff --git a/gnulib b/gnulib
index 26c5fd742f9136e2ddbd4695a9172c3fa30ea260..5ca4b90d06ed5871ed0bf7bd59dbbf23b69a00ea 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 26c5fd742f9136e2ddbd4695a9172c3fa30ea260
+Subproject commit 5ca4b90d06ed5871ed0bf7bd59dbbf23b69a00ea