Userland+Tests: Add initial riscv64 support

Author: https://github.com/spholz
Commit: 6824d2a788
Pull-request: https://github.com/SerenityOS/serenity/pull/21139
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/Hendiadyoin1
Reviewed-by: https://github.com/kleinesfilmroellchen ✅

Userland/Utilities/strace.cpp

@@ -907,6 +907,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         syscall_arg_t arg2 = 0;          // FIXME
         syscall_arg_t arg3 = 0;          // FIXME
         TODO_AARCH64();
+#elif ARCH(RISCV64)
+        syscall_arg_t syscall_index = 0; // FIXME
+        syscall_arg_t arg1 = 0;          // FIXME
+        syscall_arg_t arg2 = 0;          // FIXME
+        syscall_arg_t arg3 = 0;          // FIXME
+        TODO_RISCV64();
 #else
 #    error Unknown architecture
 #endif
@@ -924,6 +930,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 #elif ARCH(AARCH64)
         u64 res = 0; // FIXME
         TODO_AARCH64();
+#elif ARCH(RISCV64)
+        u64 res = 0; // FIXME
+        TODO_RISCV64();
 #else
 #    error Unknown architecture
 #endif