Renesas: Add support for Renesas compilers

- CC-RX for RX architecture
- CC-RL for RL78 architecture
- CC-RH for RH850 architecture

Closes: #26880

Help/variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID.rst

@@ -253,6 +253,23 @@ These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
 ``V850``
   Renesas Electronics V850 32-bit
 
+Renesas Compiler Platforms
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 4.1
+
+These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
+``Renesas``.
+
+``RH850``
+  Renesas Electronics RH850
+
+``RL78``
+  Renesas Electronics RL78
+
+``RX``
+  Renesas Electronics RX
+
 TASKING Platforms
 ^^^^^^^^^^^^^^^^^
 

Help/variable/CMAKE_LANG_COMPILER_ID.rst

@@ -42,6 +42,7 @@ Value                           Name
 ``PGI``                         The Portland Group
 ``PathScale``                   PathScale
 ``QCC``                         QNX C/C++ compiler
+``Renesas``                     `Renesas Compiler`_
 ``SCO``                         SCO OpenServer/UnixWare C/C++ Compiler
 ``SDCC``                        `Small Device C Compiler`_
 ``SunPro``                      Oracle Developer Studio
@@ -70,6 +71,7 @@ languages.
 .. _NVIDIA CUDA Compiler: https://developer.nvidia.com/cuda-llvm-compiler
 .. _Open Watcom: https://open-watcom.github.io
 .. _OrangeC Compiler: https://github.com/LADSoft/OrangeC
+.. _Renesas Compiler: https://www.renesas.com
 .. _Small Device C Compiler: https://sdcc.sourceforge.net
 .. _Tiny C Compiler: https://bellard.org/tcc
 .. _Tasking Compiler Toolsets: https://www.tasking.com