Support custom memory management macros

Users can define their custom memory management macros.

NOTE: Most external libraries support custom macros in the same way, raylib should redefine those macros to raylib ones, to unify custom memory loading. That redefinition is only implemented as example for stb_image.h in [textures] module.

Author: raysan5

src/core.c

@@ -1113,7 +1113,7 @@ void EndDrawing(void)
             unsigned char *screenData = rlReadScreenPixels(screenWidth, screenHeight);
             GifWriteFrame(screenData, screenWidth, screenHeight, 10, 8, false);
 
-            free(screenData);   // Free image data
+            RL_FREE(screenData);   // Free image data
         }
 
         if (((gifFramesCounter/15)%2) == 1)
@@ -1595,7 +1595,7 @@ void TakeScreenshot(const char *fileName)
 #endif
 
     ExportImage(image, path);
-    free(imgData);
+    RL_FREE(imgData);
 
 #if defined(PLATFORM_WEB)
     // Download file from MEMFS (emscripten memory filesystem)
@@ -1742,8 +1742,8 @@ char **GetDirectoryFiles(const char *dirPath, int *fileCount)
     ClearDirectoryFiles();
 
     // Memory allocation for MAX_DIRECTORY_FILES
-    dirFilesPath = (char **)malloc(sizeof(char *)*MAX_DIRECTORY_FILES);
-    for (int i = 0; i < MAX_DIRECTORY_FILES; i++) dirFilesPath[i] = (char *)malloc(sizeof(char)*MAX_FILEPATH_LENGTH);
+    dirFilesPath = (char **)RL_MALLOC(sizeof(char *)*MAX_DIRECTORY_FILES);
+    for (int i = 0; i < MAX_DIRECTORY_FILES; i++) dirFilesPath[i] = (char *)RL_MALLOC(sizeof(char)*MAX_FILEPATH_LENGTH);
 
     int counter = 0;
     struct dirent *ent;
@@ -1776,9 +1776,9 @@ void ClearDirectoryFiles(void)
 {
     if (dirFilesCount > 0)
     {
-        for (int i = 0; i < dirFilesCount; i++) free(dirFilesPath[i]);
+        for (int i = 0; i < dirFilesCount; i++) RL_FREE(dirFilesPath[i]);
 
-        free(dirFilesPath);
+        RL_FREE(dirFilesPath);
         dirFilesCount = 0;
     }
 }
@@ -1808,9 +1808,9 @@ void ClearDroppedFiles(void)
 {
     if (dropFilesCount > 0)
     {
-        for (int i = 0; i < dropFilesCount; i++) free(dropFilesPath[i]);
+        for (int i = 0; i < dropFilesCount; i++) RL_FREE(dropFilesPath[i]);
 
-        free(dropFilesPath);
+        RL_FREE(dropFilesPath);
 
         dropFilesCount = 0;
     }
@@ -1925,7 +1925,7 @@ void OpenURL(const char *url)
     }
     else
     {
-        char *cmd = (char *)calloc(strlen(url) + 10, sizeof(char));
+        char *cmd = (char *)RL_CALLOC(strlen(url) + 10, sizeof(char));
 
 #if defined(_WIN32)
         sprintf(cmd, "explorer %s", url);
@@ -1935,7 +1935,7 @@ void OpenURL(const char *url)
         sprintf(cmd, "open '%s'", url);
 #endif
         system(cmd);
-        free(cmd);
+        RL_FREE(cmd);
     }
 }
 
@@ -3455,11 +3455,11 @@ static void WindowDropCallback(GLFWwindow *window, int count, const char **paths
 {
     ClearDroppedFiles();
 
-    dropFilesPath = (char **)malloc(sizeof(char *)*count);
+    dropFilesPath = (char **)RL_MALLOC(sizeof(char *)*count);
 
     for (int i = 0; i < count; i++)
     {
-        dropFilesPath[i] = (char *)malloc(sizeof(char)*MAX_FILEPATH_LENGTH);
+        dropFilesPath[i] = (char *)RL_MALLOC(sizeof(char)*MAX_FILEPATH_LENGTH);
         strcpy(dropFilesPath[i], paths[i]);
     }