PostGIS trunk doesn't compile against 9.5

[robe]

I guess we can't use the ALLOC small sizes for 9.5

This is showing on winnie's 9.5 tests

prototypes  -c -o lwgeom_transform.o lwgeom_transform.c
lwgeom_transform.c: In function 'AddToPROJ4SRSCache':
lwgeom_transform.c:545:42: error: 'ALLOCSET_SMALL_SIZES' undeclared (first use in this function)
                                          ALLOCSET_SMALL_SIZES);
                                          ^
lwgeom_transform.c:545:42: note: each undeclared identifier is reported only once for each function it appears in
lwgeom_transform.c:545:42: error: too few arguments to function 'AllocSetContextCreate'
In file included from lwgeom_transform.c:18:0:
E:/jenkins/postgresql/rel/pg9.5w64gcc48/include/server/utils/memutils.h:131:22: note: declared here
 extern MemoryContext AllocSetContextCreate(MemoryContext parent,
                      ^
Makefile:61: recipe for target 'lwgeom_transform.o' failed
make[1]: *** [lwgeom_transform.o] Error 1
make[1]: Leaving directory '/projects/postgis/branches/2.5/libpgcommon'
GNUmakefile:16: recipe for target 'all' failed
make: *** [all] Error 1

So I guess 1 of two options, we can IF DEF for 9.5 or just have 9.5 go down the yee old path like 9.4

[pramsey]

Sending it down the old path seems preferable to figuring out a 9.5-only solution to the allocset issue.

[robe]

Well I think I know the 9.5-only solution I think it just has to have the multiple-args spit out I originally thought we needed for < 11, but it's probably safer to just send it down the old path, cause otherwise we'd have an extra IFDEF ugliness we'd have to get rid of eventually.

[robe]

In 16189:

Change new cache behavior to require > 9.6 instead of > 9.5, the AllocSetContextCreate structure in 9.5 doesn't support ALLOCSET_SMALL_SIZES macro so would otherwise require more ugly ifdefing.
Closes #3950