buildsys: gen_bits_syscall_h: remove top_builddir references

This script hasn't used this var in a while (it writes to stdout), so
drop all mention/usage of it.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

Makefile.in

@@ -175,7 +175,7 @@ $(top_builddir)include/bits/sysnum.h: $(top_srcdir)extra/scripts/gen_bits_syscal
 	$(Q)set -e; \
 	tmp=`mktemp $(top_builddir)include/bits/sysnum.h.XXXXXX 2>/dev/null || true`; \
 	[ -z "$$tmp" ] && tmp='$(top_builddir)include/bits/sysnum.h.new'; \
-	KERNEL_HEADERS="${KERNEL_HEADERS}" top_builddir="$(top_builddir)" CC="$(CC) $(CPU_CFLAGS)" $(SHELL) $< > $$tmp; \
+	KERNEL_HEADERS="${KERNEL_HEADERS}" CC="$(CC) $(CPU_CFLAGS)" $(SHELL) $< > $$tmp; \
 	if cmp $(top_builddir)include/bits/sysnum.h $$tmp >/dev/null 2>&1; then \
 		$(RM) $$tmp; \
 	else \

extra/scripts/gen_bits_syscall_h.sh

@@ -8,10 +8,9 @@
 
 # June 27, 2001         Manuel Novoa III
 #
-# This script expects top_builddir and CC (as used in the Makefiles) to be set
-# in the environment, and outputs the appropriate
-# $top_builddir/include/bits/sysnum.h # corresponding to
-# $top_builddir/include/asm/unistd.h to stdout.
+# This script expects  CC (as used in the Makefiles) to be set
+# in the environment, and outputs the appropriate bits/sysnum.h #
+# corresponding to asm/unistd.h to stdout.
 #
 # Warning!!! This does _no_ error checking!!!