src/sdf/ftbsdf.c: undefine 'near' for Watcom builds

Watcom defines near to its __near keyword and build fails otherwise:

src/sdf/ftbsdf.c(598): Error! E1016: Expecting identifier
src/sdf/ftbsdf.c(602): Error! E1016: Expecting identifier
src/sdf/ftbsdf.c(602): Error! E1151: Parameter count does not agree with previous definition
src/sdf/ftbsdf.c(602): Note! I2002: 'FT_Vector_Length' defined in: include/freetype/fttrigon.h(288)
src/sdf/ftbsdf.c(608): Error! E1016: Expecting identifier
src/sdf/ftbsdf.c(609): Error! E1016: Expecting identifier
src/sdf/ftbsdf.c(876): Error! E1016: Expecting identifier
src/sdf/ftbsdf.c(885): Error! E1016: Expecting identifier

diff --git a/src/sdf/ftbsdf.c b/src/sdf/ftbsdf.c
index fac3c3e..813dd64 100644
--- a/src/sdf/ftbsdf.c
+++ b/src/sdf/ftbsdf.c
@@ -191,6 +191,9 @@
    *     of a pixel.
    *
    */
+  #ifdef __WATCOMC__
+  #undef near
+  #endif
   typedef struct  ED_
   {
     FT_16D16      dist;