Use portable make variables
The usage of '$<' with BSD make results in an empty variable, therefore
compilation fails.
@@ -165,7 +165,7 @@ etags:
tools/gen_test_char@EXEEXT@: tools/gen_test_char.c
$(APR_MKDIR) tools
- $(CC_FOR_BUILD) $(CFLAGS_FOR_BUILD) $< -o $@
+ $(CC_FOR_BUILD) $(CFLAGS_FOR_BUILD) tools/gen_test_char.c -o $@
include/private/apr_escape_test_char.h: tools/gen_test_char@EXEEXT@
$(APR_MKDIR) include/private
