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/wutdevoptab/CMakeLists.txt

@@ -1,34 +0,0 @@
-cmake_minimum_required(VERSION 3.2)
-project(wutdevoptab C)
-
-add_library(wutdevoptab
-   devoptab_fs.c
-   devoptab_fs_chdir.c
-   devoptab_fs_chmod.c
-   devoptab_fs_close.c
-   devoptab_fs_dirclose.c
-   devoptab_fs_dirnext.c
-   devoptab_fs_diropen.c
-   devoptab_fs_dirreset.c
-   devoptab_fs_fchmod.c
-   devoptab_fs_fstat.c
-   devoptab_fs_fsync.c
-   devoptab_fs_getmtime.c
-   devoptab_fs_link.c
-   devoptab_fs_mkdir.c
-   devoptab_fs_open.c
-   devoptab_fs_read.c
-   devoptab_fs_rename.c
-   devoptab_fs_rmdir.c
-   devoptab_fs_seek.c
-   devoptab_fs_stat.c
-   devoptab_fs_statvfs.c
-   devoptab_fs_truncate.c
-   devoptab_fs_unlink.c
-   devoptab_fs_utils.c
-   devoptab_fs_write.c)
-
-target_include_directories(wutdevoptab PRIVATE "${WUT_ROOT}/include")
-
-install(TARGETS wutdevoptab
-        ARCHIVE DESTINATION "${CMAKE_INSTALL_PREFIX}/lib")

libraries/wutdevoptab/devoptab_fs_read.c

@@ -6,7 +6,7 @@ __wut_fs_read(struct _reent *r,
               char *ptr,
               size_t len)
 {
-   FSStatus status;
+   FSStatus status = 0;
    FSCmdBlock cmd;
    uint8_t *alignedReadBuffer;
    uint32_t bytes, bytesRead;

libraries/wutdevoptab/devoptab_fs_write.c

@@ -6,7 +6,7 @@ __wut_fs_write(struct _reent *r,
                const char *ptr,
                size_t len)
 {
-   FSStatus status;
+   FSStatus status = 0;
    FSCmdBlock cmd;
    uint8_t *alignedWriteBuffer;
    uint32_t bytes, bytesWritten;