lib: libc: arcmwdt: move ssize_t definition from the toolchain header

Until POSIX layer decoupling is done, we still need the size_t type
definition across the codebase, but it should come through sys/types.h
and not through toolchain-specific headers.

Signed-off-by: Ilya Tagunov <Ilya.Tagunov@synopsys.com>

include/zephyr/toolchain/mwdt.h

@@ -114,16 +114,6 @@
 
 #else /* defined(_ASMLANGUAGE) */
 
-/* MWDT toolchain misses ssize_t definition which is used by Zephyr */
-#ifndef _SSIZE_T_DEFINED
-#define _SSIZE_T_DEFINED
-#ifdef CONFIG_64BIT
-	typedef long ssize_t;
-#else
-	typedef int ssize_t;
-#endif
-#endif /* _SSIZE_T_DEFINED */
-
 #ifdef CONFIG_NEWLIB_LIBC
   #error "ARC MWDT doesn't support building with CONFIG_NEWLIB_LIBC as it doesn't have newlib"
 #endif /* CONFIG_NEWLIB_LIBC */

lib/libc/arcmwdt/include/sys/types.h

@@ -15,4 +15,13 @@
 #define _UID_T_DECLARED
 #define _GID_T_DECLARED
 
+#ifndef _SSIZE_T_DEFINED
+#define _SSIZE_T_DEFINED
+#ifdef CONFIG_64BIT
+typedef long ssize_t;
+#else  /* CONFIG_64BIT */
+typedef int ssize_t;
+#endif /* CONFIG_64BIT */
+#endif /* _SSIZE_T_DEFINED */
+
 #endif /* LIB_LIBC_ARCMWDT_INCLUDE_SYS_TYPES_H_ */