Disable Cland and LLVM plugins on riscv64

[..]
make[1]: Leaving directory '/builddir/build/BUILD/annobin-10.91/clang-plugin'
In file included from annobin.cpp:15:
In file included from /usr/include/clang/Frontend/FrontendPluginRegistry.h:16:
In file included from /usr/include/clang/Frontend/FrontendAction.h:21:
In file included from /usr/include/clang/Basic/LLVM.h:21:
In file included from /usr/include/llvm/Support/Casting.h:17:
In file included from /usr/include/llvm/ADT/Optional.h:19:
In file included from /usr/include/llvm/ADT/Hashing.h:49:
/usr/include/llvm/Support/SwapByteOrder.h:17:10: fatal error: 'cstddef' file not found
         ^~~~~~~~~
1 error generated.
make[1]: *** [Makefile:33: annobin-for-clang.so] Error 1
[..]

Signed-off-by: David Abdurachmanov <davidlt@rivosinc.com>

annobin.spec

@@ -2,7 +2,7 @@
 Name:    annobin
 Summary: Annotate and examine compiled binary files
 Version: 10.91
-Release: 1%{?dist}
+Release: 1.0.riscv64%{?dist}
 License: GPLv3+
 URL: https://sourceware.org/annobin/
 # Maintainer: nickc@redhat.com
@@ -24,13 +24,21 @@ URL: https://sourceware.org/annobin/
 %bcond_with debuginfod
 
 # Use "--without clangplugin" to disable the building of the annobin plugin for Clang.
+%ifnarch riscv64
 %bcond_without clangplugin
+%else
+%bcond_with clangplugin
+%endif
 
 # Use "--without gccplugin" to disable the building of the annobin plugin for GCC.
 %bcond_without gccplugin
 
 # Use "--without llvmplugin" to disable the building of the annobin plugin for LLVM.
+%ifnarch riscv64
 %bcond_without llvmplugin
+%else
+%bcond_with llvmplugin
+%endif
 
 # Set this to zero to disable the requirement for a specific version of gcc.
 # This should only be needed if there is some kind of problem with the version
@@ -508,6 +516,9 @@ fi
 #---------------------------------------------------------------------------------
 
 %changelog
+* Sat Oct 22 2022 David Abdurachmanov  <davidlt@rivosinc.com> - 10.91-1.0.riscv64
+- Disable Clang and LLVM plugings on riscv64
+
 * Fri Oct 21 2022 Yara Ahmad  <yahmad@redhat.com> - 10.91-1
 - Rebase to annobin-10.91
   - Tests: Fix future-test so that it properly handles the situation where the compiler does not support the new options.