redefined warning notice

[robe]

-I/projects/CGAL/rel-sfcgal-1.1.0w64gcc48/include -DHAVE_SFCGAL -I/projects/json-c/rel-0.12w64gcc48/include -I/projects/pcre/rel-8.33w64gcc48/include -I/projects/postgresql/rel/pg9.4w64gcc48/include -I/projects/rel-libiconv-1.13.1w64gcc48/include -fPIC -I/projects/CGAL/rel-sfcgal-1.1.0w64gcc48/include -DHAVE_SFCGAL -I. -I./ -Ie:/jenkins/postgresql/rel/pg9.4w64gcc48/include/server -Ie:/jenkins/postgresql/rel/pg9.4w64gcc48/include/internal -I./src/include/port/win32 -DEXEC_BACKEND -I/projects/libxml/rel-libxml2-2.7.8w64gcc48/include/libxml2  "-I/src/include/port/win32" -Ie:/jenkins/postgresql/rel/pg9.4w64gcc48/include/server/port/win32  -c -o postgis_topology.o postgis_topology.c
postgis_topology.c:1:0: warning: -fPIC ignored for target (all code is position independent) [enabled by default]
 /**********************************************************************
 ^
postgis_topology.c:26:0: warning: "POSTGIS_DEBUG_LEVEL" redefined [enabled by default]
 #define POSTGIS_DEBUG_LEVEL 1
 ^
In file included from postgis_topology.c:22:0:
../postgis_config.h:123:0: note: this is the location of the previous definition
 #define POSTGIS_DEBUG_LEVEL 0
 ^

gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-