strparse: switch to curl_off_t as base data type

- add hex and octal parsers to the Curl_str_* family
- make curlx_strtoofft use these parsers
- remove all use of strtol() and strtoul() in library code
- generally use Curl_str_* more than strtoofft, for stricter parsing
- supports 64-bit universally, instead of 'long' which differs in size
  between platforms

Extended the unit test 1664 to verify hex and octal parsing.

Closes #16336

lib/cookie.c

@@ -80,7 +80,6 @@ Example set of cookies:
 #include "sendf.h"
 #include "slist.h"
 #include "share.h"
-#include "strtoofft.h"
 #include "strcase.h"
 #include "curl_get_line.h"
 #include "curl_memrchr.h"
@@ -89,6 +88,7 @@ Example set of cookies:
 #include "fopen.h"
 #include "strdup.h"
 #include "llist.h"
+#include "strparse.h"
 
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
@@ -708,21 +708,22 @@ parse_cookie_header(struct Curl_easy *data,
          * client should discard the cookie. A value of zero means the
          * cookie should be discarded immediately.
          */
-        CURLofft offt;
+        int rc;
         const char *maxage = valuep;
-        offt = curlx_strtoofft((*maxage == '\"') ?
-                               &maxage[1] : &maxage[0], NULL, 10,
-                               &co->expires);
-        switch(offt) {
-        case CURL_OFFT_FLOW:
+        if(*maxage == '\"')
+          maxage++;
+        rc = Curl_str_number(&maxage, &co->expires, CURL_OFF_T_MAX);
+
+        switch(rc) {
+        case STRE_OVERFLOW:
           /* overflow, used max value */
           co->expires = CURL_OFF_T_MAX;
           break;
-        case CURL_OFFT_INVAL:
+        default:
           /* negative or otherwise bad, expire */
           co->expires = 1;
           break;
-        case CURL_OFFT_OK:
+        case STRE_OK:
           if(!co->expires)
             /* already expired */
             co->expires = 1;
@@ -915,16 +916,8 @@ parse_netscape(struct Cookie *co,
       }
       break;
     case 4:
-      {
-        char *endp;
-        const char *p;
-        /* make sure curlx_strtoofft won't read past the current field */
-        for(p = ptr; p < &ptr[len] && ISDIGIT(*p); ++p)
-          ;
-        if(p == ptr || p != &ptr[len] ||
-           curlx_strtoofft(ptr, &endp, 10, &co->expires) || endp != &ptr[len])
-          return CERR_RANGE;
-      }
+      if(Curl_str_number(&ptr, &co->expires, CURL_OFF_T_MAX))
+        return CERR_RANGE;
       break;
     case 5:
       co->name = Curl_memdup0(ptr, len);