trurl: support compiling with old versions of Visual Studio

- Define bool type and remove mixed declarations for old versions of
  Visual Studio.

This supports compiling trurl with old versions of Visual Studio by
using cl at the command line only. The winbuild solution still requires
recent versions of Visual Studio.

Closes #268

trurl.c

@@ -26,11 +26,21 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <stdbool.h>
 #include <curl/curl.h>
 #include <curl/mprintf.h>
 #include <stdint.h>
 
+#if defined(_MSC_VER) && (_MSC_VER < 1800)
+typedef enum {
+  bool_false = 0,
+  bool_true  = 1
+} bool;
+#define false bool_false
+#define true  bool_true
+#else
+#include <stdbool.h>
+#endif
+
 #include <locale.h> /* for setlocale() */
 
 #include "version.h"
@@ -980,11 +990,12 @@ static void trim(struct option *o)
 {
   struct curl_slist *node;
   for(node = o->trim_list; node; node = node->next) {
+    char *ptr;
     char *instr = node->data;
     if(strncmp(instr, "query", 5))
       /* for now we can only trim query components */
       errorf(o, ERROR_TRIM, "Unsupported trim component: %s", instr);
-    char *ptr = strchr(instr, '=');
+    ptr = strchr(instr, '=');
     if(ptr && (ptr > instr)) {
       /* 'ptr' should be a fixed string or a pattern ending with an
          asterisk */
@@ -1068,6 +1079,7 @@ static struct string *memdupdec(char *source, size_t len, bool json)
   int right_len = 0;
   int left_len = 0;
   char *str;
+  struct string *ret;
 
   left = strurldecode(source, (int)(sep ? (size_t)(sep - source) : len),
                       &left_len);
@@ -1094,7 +1106,7 @@ static struct string *memdupdec(char *source, size_t len, bool json)
   }
   curl_free(right);
   curl_free(left);
-  struct string *ret = malloc(sizeof(struct string));
+  ret = malloc(sizeof(struct string));
   if(!ret) {
     return NULL;
   }
@@ -1200,10 +1212,11 @@ static void qpair2query(CURLU *uh, struct option *o)
 /* sort case insensitively */
 static int cmpfunc(const void *p1, const void *p2)
 {
+  int i;
   int len = (int)((((struct string *)p1)->len) < (((struct string *)p2)->len)?
                   (((struct string *)p1)->len) : (((struct string *)p2)->len));
 
-  for(int i = 0; i < len; i++) {
+  for(i = 0; i < len; i++) {
     char c1 = ((struct string *)p1)->str[i] | ('a' - 'A');
     char c2 = ((struct string *)p2)->str[i] | ('a' - 'A');
     if(c1 != c2)