config: introduce set_nfactor() and use it to call set_algorithm_nfactor().

Had two bugs:

1. Will not compile due to unknown algorithm_t size.
2. nfactor is set to 0 (bad calling, fix later).

So squashed two commits:

1. algorithm: move algorithm_t definition to header.
2. config: if --nfactor is specified, properly set algorithm->nfactor.

algorithm.c

@@ -12,11 +12,6 @@
 #include <inttypes.h>
 #include <string.h>
 
-typedef struct algorithm_t {
-    char    name[20]; /* Human-readable identifier */
-    uint8_t nfactor;  /* N factor (CPU/Memory tradeoff parameter) */
-} algorithm_t;
-
 void set_algorithm(algorithm_t* algo, const char* newname) {
     strncpy(algo->name, newname, sizeof(algo->name));
     algo->name[sizeof(algo->name) - 1] = '\0';

algorithm.h

@@ -6,7 +6,10 @@
 /* Describes the Scrypt parameters and hashing functions used to mine
  * a specific coin.
  */
-typedef struct algorithm_t algorithm_t;
+typedef struct _algorithm_t {
+    char    name[20]; /* Human-readable identifier */
+    uint8_t nfactor;  /* N factor (CPU/Memory tradeoff parameter) */
+} algorithm_t;
 
 /* Set default parameters based on name. */
 void set_algorithm(algorithm_t* algo, const char* name);

sgminer.c

@@ -1018,6 +1018,12 @@ static char *set_algo(const char *arg)
 	return NULL;
 }
 
+static char *set_nfactor(const char *arg)
+{
+	set_algorithm_nfactor(algorithm, (uint8_t)atoi(arg));
+	return NULL;
+}
+
 static char *set_api_allow(const char *arg)
 {
 	opt_set_charp(arg, &opt_api_allow);
@@ -1069,7 +1075,7 @@ static char *set_null(const char __maybe_unused *arg)
 static struct opt_table opt_config_table[] = {
 	OPT_WITH_ARG("--algorithm",
 		     set_algo, NULL, NULL,
-		     "Set mining algorithm to most common defaults, default: static"),
+		     "Set mining algorithm and most common defaults, default: static"),
 	OPT_WITH_ARG("--api-allow",
 		     set_api_allow, NULL, NULL,
 		     "Allow API access only to the given list of [G:]IP[/Prefix] addresses[/subnets]"),
@@ -1122,9 +1128,6 @@ static struct opt_table opt_config_table[] = {
 			opt_set_bool, &opt_compact,
 			"Use compact display without per device statistics"),
 #endif
-	OPT_WITH_ARG("--nfactor",
-		     set_int_0_to_9999, opt_show_intval, &opt_nfactor,
-		     "Set scrypt N-factor parameter, default: 10. Currently use 11 for vertcoin!"),
 	OPT_WITHOUT_ARG("--debug|-D",
 		     enable_debug, &opt_debug,
 		     "Enable debug output"),
@@ -1228,6 +1231,9 @@ static struct opt_table opt_config_table[] = {
 	OPT_WITHOUT_ARG("--net-delay",
 			opt_set_bool, &opt_delaynet,
 			"Impose small delays in networking to not overload slow routers"),
+	OPT_WITH_ARG("--nfactor",
+		     set_nfactor, NULL, NULL,
+		     "Override default scrypt N-factor parameter."),
 #ifdef HAVE_ADL
 	OPT_WITHOUT_ARG("--no-adl",
 			opt_set_bool, &opt_noadl,
@@ -7764,7 +7770,7 @@ int main(int argc, char *argv[])
 	int i, j;
 	char *s;
 
-	/* This dangerous functions tramples random dynamically allocated
+	/* This dangerous function tramples random dynamically allocated
 	 * variables so do it before anything at all */
 	if (unlikely(curl_global_init(CURL_GLOBAL_ALL)))
 		quit(1, "Failed to curl_global_init");
@@ -7842,6 +7848,8 @@ int main(int argc, char *argv[])
 	strcat(sgminer_path, "\\");
 #endif
 
+	algorithm = (algorithm_t *)alloca(sizeof(algorithm_t));
+
 	devcursor = 8;
 	logstart = devcursor + 1;
 	logcursor = logstart + 1;