Prefer new over malloc

The former cannot return NULL and will allow use of scoped pointers.

src/string_util.cpp

@@ -372,9 +372,7 @@ char* s3fs_base64(const unsigned char* input, size_t length)
   if(!input || 0 == length){
     return NULL;
   }
-  if(NULL == (result = reinterpret_cast<char*>(malloc((((length / 3) + 1) * 4 + 1) * sizeof(char))))){
-    return NULL; // ENOMEM
-  }
+  result = new char[((length / 3) + 1) * 4 + 1];
 
   unsigned char parts[4];
   size_t rpos;
@@ -422,9 +420,7 @@ unsigned char* s3fs_decode64(const char* input, size_t* plength)
   if(!input || 0 == strlen(input) || !plength){
     return NULL;
   }
-  if(NULL == (result = reinterpret_cast<unsigned char*>(malloc((strlen(input) + 1))))){
-    return NULL; // ENOMEM
-  }
+  result = new unsigned char[strlen(input) + 1];
 
   unsigned char parts[4];
   size_t input_len = strlen(input);