bzip2: move ifdef handling to Makefile COBJS-$(...)

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/lib_generic/Makefile b/lib_generic/Makefile
index 3f04022..686601c 100644
--- a/lib_generic/Makefile
+++ b/lib_generic/Makefile
@@ -26,11 +26,11 @@
 LIB	= $(obj)libgeneric.a
 
 COBJS-$(CONFIG_ADDR_MAP) += addr_map.o
-COBJS-y += bzlib.o
-COBJS-y += bzlib_crctable.o
-COBJS-y += bzlib_decompress.o
-COBJS-y += bzlib_randtable.o
-COBJS-y += bzlib_huffman.o
+COBJS-$(CONFIG_BZIP2) += bzlib.o
+COBJS-$(CONFIG_BZIP2) += bzlib_crctable.o
+COBJS-$(CONFIG_BZIP2) += bzlib_decompress.o
+COBJS-$(CONFIG_BZIP2) += bzlib_randtable.o
+COBJS-$(CONFIG_BZIP2) += bzlib_huffman.o
 COBJS-y += crc16.o
 COBJS-y += crc32.o
 COBJS-y += ctype.o