make PK_MAX_RETRIES a config option

src/headers/tomcrypt_custom.h

@@ -500,6 +500,11 @@
 #if defined(LTC_MECC) || defined(LTC_MRSA) || defined(LTC_MDSA) || defined(LTC_MKAT)
    /* Include the MPI functionality?  (required by the PK algorithms) */
    #define LTC_MPI
+
+   #ifndef LTC_PK_MAX_RETRIES
+      /* iterations limit for retry-loops */
+      #define LTC_PK_MAX_RETRIES  20
+   #endif
 #endif
 
 #ifdef LTC_MRSA

src/headers/tomcrypt_pk.h

@@ -17,9 +17,6 @@ enum {
 /* Indicates standard output formats that can be read e.g. by OpenSSL or GnuTLS */
 #define PK_STD          0x1000
 
-/* iterations limit for retry-loops */
-#define PK_MAX_RETRIES  20
-
 int rand_prime(void *N, long len, prng_state *prng, int wprng);
 
 #ifdef LTC_SOURCE