Makefile: remove uneeded (and faulty) logic around CFLAGS_HOST

The CFLAG_HOST variable was added in #307, and
some Makefile logic was added to define the variable to be blank if
the included Macros file does not define it.

However, the Make syntax is wrong, as 'ifndef' takes a variable name and not
a reference to a variable [1], so

    ifndef $(CFLAGS_HOST)

should have been written

    ifndef CFLAGS_HOST

The effect of this error is to invert the logic of the check (!) since if
CFLAGS_HOST is defined, Make will check if a variable with name equal to
whatever CFLAGS_HOST is defined to be exists, which will most probably be false,
and the conditional will then evaluate to true and CFLAG_HOSTS will be redefined
to be blank, defeating the whole purpose of the flag.

Since there's no harm in Make referencing and empty variable, fix this by just
removing the conditional check.

[1] https://www.gnu.org/software/make/manual/html_node/Conditional-Syntax.html

configuration/scripts/Makefile

@@ -119,10 +119,6 @@ db_flags:
 # the needed macros
 #-------------------------------------------------------------------------------
 
-ifndef $(CFLAGS_HOST)
-  CFLAGS_HOST :=
-endif
-
 $(DEPGEN): $(OBJS_DEPGEN)
 	@ echo "Building makdep"
 	$(SCC) -o $@ $(CFLAGS_HOST) $<