MinGW/Cygwin build snags

First, when I tried to add an Assert() call to a file in src/port, a MinGW-w64
build failed like this:

Creating library file: libpostgres.a
../../src/port/libpgport_srv.a(fls_srv.o): In function `fls':
/home/nm/src/pg/mingw-postgresql/src/port/fls.c:63: undefined reference to `__imp_assert_enabled'

Since src/makefiles/Makefile.win32 does not set BUILDING_DLL for src/port,
PGDLLIMPORT is set improperly for code to be linked directly into the backend.
Makefile.win32 does set BUILDING_DLL for src/common.  (Makefile.cygwin has the
same discrepancy, though I haven't checked whether it causes an actual build
failure there.  The MSVC build system sets BUILDING_DLL for both src/port and
src/common files.)  This affects any reference to a data symbol from src/port.
The fix is straightforward enough: cause Makefile.{win32,cygwin} to treat
src/port like src/common.


Second, src/template/{win32,cygwin} completely replaces LDFLAGS, so overriding
LDFLAGS on the "configure" command line is ineffective.  Those scripts should
instead add to the existing LDFLAGS, like other templates do for CPPFLAGS.
Several other templates completely override CFLAGS; that's undesirable for the
same reason.  I don't have ready access to those affected configurations, so
I'm leaving the CFLAGS damage alone.  A fix for the Makefile.win32 half of the
original problem appeared as part of a larger patch:
http://www.postgresql.org/message-id/flat/86sk8845pl.fsf@ds4.des.no


Both of these changes fix bugs, but I plan not to back-patch.  Builds that
work today won't see any change, and I found no other user reports.

--
Noah Misch
EnterpriseDB                                 http://www.enterprisedb.com