gdal build on solaris

Hi,

Configure seems to be a little bit broken for solaris.  I had to add 
"-D_REENTRANT" manually to CXX_OPTFLAGS and C_OPTFLAGS in GDALmake.opt 
after running configure before it would make: on our solaris machine, 
localtime_r (in time.h) is bracketed by:

#if    defined(__EXTENSIONS__) || defined(_REENTRANT) || 
(_POSIX_C_SOURCE - 0 >= 199506L)

This localtime_r function is used by VSILocalTime in cpl_vsisimple.cpp 
if HAVE_LOCALTIME_R is set to 1 during configure (it is on solaris). 
I'm not sure if REENTRANT was the right define to add though, or if 
configure should have not set HAVE_LOCALTIME_R at all (when I added the 
REENTRANT it compiled, but I don't know if it will have weird side 
effects). 

Gillian