config.mk: Remove unused HPATH

This variable is not unused anywhere.

Signed-off-by: Shinya Kuribayashi <skuribay@pobox.com>
diff --git a/config.mk b/config.mk
index f2c2c6c..a9973a4 100644
--- a/config.mk
+++ b/config.mk
@@ -196,7 +196,7 @@
 
 #########################################################################
 
-export	HPATH HOSTCC HOSTCFLAGS CROSS_COMPILE \
+export	HOSTCC HOSTCFLAGS CROSS_COMPILE \
 	AS LD CC CPP AR NM STRIP OBJCOPY OBJDUMP MAKE
 export	TEXT_BASE PLATFORM_CPPFLAGS PLATFORM_RELFLAGS CPPFLAGS CFLAGS AFLAGS