compile with configure --enable-debug is broken

[robe]

I thought I had this issue before so hopefully this isn't a redundant ticket.

When doing

./configure  --enable-debug

Things don't compile. Breaks in geography.

gserialized_gist_2d.c:1:0: warning: -fPIC ignored for target (all code is position independent) [enabled by default]
 /**********************************************************************
 ^
In file included from C:/MING64~1/projects/POSTGR~1/rel/PG9~2.6W6/include/server/postgres.h:48:0,
                 from gserialized_gist_2d.c:41:
gserialized_gist_2d.c: In function 'gserialized_datum_predicate_box2df_geom_2d':
gserialized_gist_2d.c:644:68: error: 'b1' undeclared (first use in this function)
   POSTGIS_DEBUGF(3, "got boxes %s and %s", br1 ? box2df_to_string(&b1) : "(null)", br2 ? box2df_to_string(&b2) : "(null)");
                                                                    ^
C:/MING64~1/projects/POSTGR~1/rel/PG9~2.6W6/include/server/utils/elog.h:107:14: note: in definition of macro 'ereport_domain'
    errfinish rest; \
              ^
../libpgcommon/lwgeom_pg.h:48:25: note: in expansion of macro 'ereport'
                         ereport((level < 1 || level > 5) ? DEBUG5 : (LOG - level), (errmsg_internal("[%s:%s:%d] " msg, __FILE__, __func__, __LINE__, __VA_ARGS__))); \
                         ^
gserialized_gist_2d.c:644:3: note: in expansion of macro 'POSTGIS_DEBUGF'
   POSTGIS_DEBUGF(3, "got boxes %s and %s", br1 ? box2df_to_string(&b1) : "(null)", br2 ? box2df_to_string(&b2) : "(null)");
   ^
gserialized_gist_2d.c:644:68: note: each undeclared identifier is reported only once for each function it appears in
   POSTGIS_DEBUGF(3, "got boxes %s and %s", br1 ? box2df_to_string(&b1) : "(null)", br2 ? box2df_to_string(&b2) : "(null)");
                                                                    ^
C:/MING64~1/projects/POSTGR~1/rel/PG9~2.6W6/include/server/utils/elog.h:107:14: note: in definition of macro 'ereport_domain'
    errfinish rest; \
              ^
../libpgcommon/lwgeom_pg.h:48:25: note: in expansion of macro 'ereport'
                         ereport((level < 1 || level > 5) ? DEBUG5 : (LOG - level), (errmsg_internal("[%s:%s:%d] " msg, __FILE__, __func__, __LINE__, __VA_ARGS__))); \
                         ^
gserialized_gist_2d.c:644:3: note: in expansion of macro 'POSTGIS_DEBUGF'
   POSTGIS_DEBUGF(3, "got boxes %s and %s", br1 ? box2df_to_string(&b1) : "(null)", br2 ? box2df_to_string(&b2) : "(null)");
   ^
<builtin>: recipe for target 'gserialized_gist_2d.o' failed
make[1]: *** [gserialized_gist_2d.o] Error 1
make[1]: Leaving directory '/projects/postgis/branches/2.3/postgis'
GNUmakefile:16: recipe for target 'all' failed
make: *** [all] Error 1

[robe]

In 15053:

get rid of undeclared variable in POSTGIS_DEBUGF
compile with configure --enable-debug is broken
closes #3618