*: mass renaming of USE_XXXX to IF_XXXX
and SKIP_XXXX to IF_NOT_XXXX - the second one was especially
badly named. It was not skipping anything!

diff --git a/util-linux/hexdump.c b/util-linux/hexdump.c
index 48edd70..98d1ac2 100644
--- a/util-linux/hexdump.c
+++ b/util-linux/hexdump.c
@@ -41,7 +41,7 @@
 
 static const char add_first[] ALIGN1 = "\"%07.7_Ax\n\"";
 
-static const char hexdump_opts[] ALIGN1 = "bcdoxCe:f:n:s:v" USE_FEATURE_HEXDUMP_REVERSE("R");
+static const char hexdump_opts[] ALIGN1 = "bcdoxCe:f:n:s:v" IF_FEATURE_HEXDUMP_REVERSE("R");
 
 static const struct suffix_mult suffixes[] = {
 	{ "b", 512 },