lib: cpp: Rename CONFIG_RTTI to CONFIG_CPP_RTTI

The Kconfig `CONFIG_RTTI` symbol enables the C++ Run-Time Type
Information (RTTI) support and is a feature of the standard C++
library; therefore, it should be prefixed with `CPP_` as with the rest
of the C++-specific symbols.

This commit renames the Kconfig `CONFIG_RTTI` symbol to
`CONFIG_CPP_RTTI` in order to better align with the other existing C++
Kconfig symbols, and deprecates the old `CONFIG_RTTI` symbol.

Signed-off-by: Stephanos Ioannidis <stephanos.ioannidis@nordicsemi.no>

lib/cpp/Kconfig

@@ -81,7 +81,7 @@ config CPP_EXCEPTIONS
 	help
 	  This option enables support of C++ exceptions.
 
-config RTTI
+config CPP_RTTI
 	bool "C++ RTTI support"
 	help
 	  This option enables support of C++ RTTI.

lib/cpp/Kconfig.deprecated

@@ -24,6 +24,15 @@ config EXCEPTIONS
 
 	  [DEPRECATED] Select CPP_EXCEPTIONS instead.
 
+config RTTI
+	bool "[DEPRECATED] C++ RTTI support"
+	select CPP_RTTI
+	select DEPRECATED
+	help
+	  This option enables support of C++ RTTI.
+
+	  [DEPRECATED] Select CPP_RTTI instead.
+
 endif # LIB_CPLUSPLUS
 
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