2.5.1 on FreeBSD 9-Stable

[Graham Menhennitt]

I thought I'd try building GnuCash 2.5.1 on FreeBSD 9-STable. I copied
the port directory, changed the version to 2.5.1, and fixed the file
size and SHA256 values to suit. I then started the build. It progresses
for a few seconds and then exits with an error:

libtool: compile:  cc -DHAVE_CONFIG_H -I. -I../../.. -I../../../lib/libc
-I../../../src -pthread -I/usr/local/include/glib-2.0
-I/usr/local/include -DG_LOG_DOMAIN=\"qof\" -I/usr/local/include
-Wdeclaration-after-statement -Wno-pointer-sign -D_FORTIFY_SOURCE=2 -O2
-pipe -fno-strict-aliasing -Wall -Wunused -Wmissing-prototypes
-Wmissing-declarations -Wno-unused -MT gnc-date.lo -MD -MP -MF
.deps/gnc-date.Tpo -c gnc-date.c  -fPIC -DPIC -o .libs/gnc-date.o
gnc-date.c: In function 'gnc_localtime_r':
gnc-date.c:310: error: lvalue required as left operand of assignment
gnc-date.c:314: error: 'daylight' undeclared (first use in this function)
gnc-date.c:314: error: (Each undeclared identifier is reported only once
gnc-date.c:314: error: for each function it appears in.)
gnc-date.c:319: error: wrong type argument to unary minus
gmake[5]: *** [gnc-date.lo] Error 1

I can't see the variables "timezone" and "daylight" declared anywhere so
I'm not surprised that it doesn't compile. How does this work on Linux?
Are they globals or something? If so, where are they declared?

Thanks,
    Graham