First pass at adopting a devkitPro-style build system, see details:

- Added wut_rules and wut/rpx/rpl.specs to share/
- Replaced wut's CMake-based buildsystem with a standard Makefile
- Conflated all wut libraries into a single libwut.a library
- wut's old buildsystems (CMake & plain make) are broken as a result,
  this will be fixed in the future
- Docs, tests and samples are not buildable either at the moment
- wutcrt/wutnewlib:
  - RPX start function is __rpx_start, while RPL is __rpl_start
  - __init/fini_wut_* functions are no longer weak
  - __init_wut/__fini_wut are instead weak
  - Removed _exit implementation
  - exit syscall now points to _Exit instead of pointing to itself
- wutstdc++:
  - Renamed .cc files to .cpp
  - Temporarily disabled, due to an issue that will be addressed shortly
- wutdevoptab:
  - Fixed uninitialized variable warnings in __wut_fs_read/write

libraries/wutmalloc/CMakeLists.txt

@@ -1,9 +0,0 @@
-cmake_minimum_required(VERSION 3.2)
-project(wutmalloc C)
-
-add_library(wutmalloc
-   wut_malloc.c)
-target_include_directories(wutmalloc PRIVATE "${WUT_ROOT}/include")
-
-install(TARGETS wutmalloc
-        ARCHIVE DESTINATION "${CMAKE_INSTALL_PREFIX}/lib")

libraries/wutmalloc/wut_malloc.c

@@ -5,7 +5,7 @@
 #include <string.h>
 
 // Limit sbrk heap to 128kb
-uint32_t __attribute__((weak)) __wut_heap_max_size = 128 * 1024;
+uint32_t __wut_heap_max_size = 128 * 1024;
 
 void *
 _malloc_r(struct _reent *r, size_t size)