Revert "BLI: Refactor vector types & functions to use templates"

Reverted because the commit removes a lot of commits.

This reverts commit a2c1c368af.

source/blender/blenlib/BLI_buffer.h

@@ -74,7 +74,7 @@ enum {
 /**
  * \note Never decreases the amount of memory allocated.
  */
-void BLI_buffer_resize(BLI_Buffer *buffer, const size_t new_count);
+void BLI_buffer_resize(BLI_Buffer *buffer, size_t new_count);
 
 /**
  * Ensure size, throwing away old data, respecting #BLI_BUFFER_USE_CALLOC.
@@ -83,7 +83,7 @@ void BLI_buffer_resize(BLI_Buffer *buffer, const size_t new_count);
  * - Ignored (malloc'd).
  * - Cleared (when #BLI_BUFFER_USE_CALLOC is set).
  */
-void BLI_buffer_reinit(BLI_Buffer *buffer, const size_t new_count);
+void BLI_buffer_reinit(BLI_Buffer *buffer, size_t new_count);
 
 /**
  * Append an array of elements.