adding "ftbbox" to build rules
diff --git a/src/base/rules.mk b/src/base/rules.mk
index 91ac007..af62ec2 100644
--- a/src/base/rules.mk
+++ b/src/base/rules.mk
@@ -47,7 +47,8 @@ BASE_SRC := $(BASE_)ftcalc.c \
# symbols is used by the application.
#
BASE_EXT_SRC := $(BASE_)ftglyph.c \
- $(BASE_)ftmm.c
+ $(BASE_)ftmm.c \
+ $(BASE_)ftbbox.c
# Default extensions objects
#