BUG #12869: PostGIS 2.2 can't compile against 9.5 dev branch

The following bug has been logged on the website:

Bug reference: 12869
Logged by: Regina Obe
Email address: lr(at)pcorp(dot)us
PostgreSQL version: Unsupported/Unknown
Operating system: Debian and Mingw-w64
Description:

I think something changed in the past 7 days to cause our PostGIS 2.2/9.5
compile to fail.

The PostGIS debian Jenkins bot pulls the latest snapshot of 9.5 and compiles
our upcoming PostGIS 2.2 trunk against it every weekend. This weekend, it
failed to compile. I'm not sure if it's something that needs changing in
PostGIS code or some issue in 9.5 recent code changes.

The error we get is this:

/pg9.5w64/include/postgresql/internal -D_GNU_SOURCE -c -o lwgeom_geos.o
lwgeom_geos.c
lwgeom_geos.c: In function ‘errorIfGeometryCollection’:
lwgeom_geos.c:1730: error: ‘DBL_DIG’ undeclared (first use in this
function)
lwgeom_geos.c:1730: error: (Each undeclared identifier is reported only
once
lwgeom_geos.c:1730: error: for each function it appears in.)
make[1]: *** [lwgeom_geos.o] Error 1
make[1]: Leaving directory
`/var/lib/jenkins/workspace/postgis/regress_pgdev/branches/2.2/postgis'
make: *** [all] Error 1

I also tried on my windows desktop pulling latest 9.5 snapshot and compiling
under mingw-w64 and get similar error.

lwgeom_geos.c: In function 'errorIfGeometryCollection':
lwgeom_geos.c:1730:46: error: 'DBL_DIG' undeclared (first use in this
function)
hintwkt = lwgeom_to_wkt(lwgeom, WKT_SFSQL, DBL_DIG, &hintsz);

Other versions of PostgreSQL are not affected.

I have the issue in our bug tracker as well here:

http://trac.osgeo.org/postgis/ticket/3079