tools/env: use lib/crc32.c directly

Instead of linking the file into $(obj) tree use directly the source file.
This also prevents littered source tree if building not out-of-tree.

Signed-off-by: Andreas Bießmann <biessmann@corscience.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/tools/env/Makefile b/tools/env/Makefile
index 2f7a59c..28b73da 100644
--- a/tools/env/Makefile
+++ b/tools/env/Makefile
@@ -23,7 +23,7 @@
 
 include $(TOPDIR)/config.mk
 
-HOSTSRCS := $(obj)crc32.c  fw_env.c  fw_env_main.c
+HOSTSRCS := $(SRCTREE)/lib/crc32.c  fw_env.c  fw_env_main.c
 HEADERS	:= fw_env.h
 
 # Compile for a hosted environment on the target
@@ -43,10 +43,7 @@
 	$(HOSTCC) $(HOSTCFLAGS_NOPED) $(HOSTLDFLAGS) -o $@ $(HOSTSRCS)
 
 clean:
-	rm -f $(obj)fw_printenv $(obj)crc32.c
-
-$(obj)crc32.c:
-	ln -s $(src)../../lib/crc32.c $(obj)crc32.c
+	rm -f $(obj)fw_printenv
 
 #########################################################################