there's no need to check out on function entry

...someone could then do something like this...

unsigned char* out = NULL;
unsigned long len = 0;
while(ecc_ansi_x963_export(key, out, &len) == CRYPT_BUFFER_OVERFLOW &&
	len == 0) {
  out = malloc(len);
}

...as if someone would ever like to do something like that...

src/pk/ecc/ecc_ansi_x963_export.c

@@ -19,7 +19,7 @@
 /**
   @file ecc_ansi_x963_export.c
   ECC Crypto, Tom St Denis
-*/  
+*/
 
 #ifdef LTC_MECC
 
@@ -35,7 +35,6 @@ int ecc_ansi_x963_export(ecc_key *key, unsigned char *out, unsigned long *outlen
    unsigned long numlen, xlen, ylen;
 
    LTC_ARGCHK(key    != NULL);
-   LTC_ARGCHK(out    != NULL);
    LTC_ARGCHK(outlen != NULL);
 
    if (ltc_ecc_is_valid_idx(key->idx) == 0) {
@@ -54,6 +53,8 @@ int ecc_ansi_x963_export(ecc_key *key, unsigned char *out, unsigned long *outlen
       return CRYPT_BUFFER_OVERFLOW;
    }
 
+   LTC_ARGCHK(out    != NULL);
+
    /* store byte 0x04 */
    out[0] = 0x04;