libiproute: rename invarg(a,b) to invarg_1_to_2(a,b)

invarg(a,b) - "invalid argument", but how a and b enter the message?

invarg_1_to_2(a,b) is somewhat easier to read: "invalid argument 'a' to 'b'"

Audit of usage revealed a number of bad uses, with too long messages.

   text	   data	    bss	    dec	    hex	filename
 938848	    932	  17448	 957228	  e9b2c	busybox_old
 938788	    932	  17448	 957168	  e9af0	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/libiproute/utils.h b/networking/libiproute/utils.h
index cd15b70..9bbed64 100644
--- a/networking/libiproute/utils.h
+++ b/networking/libiproute/utils.h
@@ -74,7 +74,7 @@
 	rt_addr_n2a(af, addr, buf, buflen)
 #endif
 
-void invarg(const char *, const char *) NORETURN;
+void invarg_1_to_2(const char *, const char *) NORETURN;
 void duparg(const char *, const char *) NORETURN;
 void duparg2(const char *, const char *) NORETURN;
 int inet_addr_match(const inet_prefix *a, const inet_prefix *b, int bits);