Fix riscv64 detection in system_check.cmake

Author: felixonmars

cmake/system_check.cmake

@@ -44,6 +44,8 @@ elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "mips64.*")
   set(MIPS64 1)
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "loongarch64.*")
   set(LOONGARCH64 1)
+elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "riscv64.*")
+  set(RISCV64 1)
 elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "amd64.*|x86_64.*|AMD64.*")
   if (NOT BINARY)
     if("${CMAKE_SIZEOF_VOID_P}" EQUAL "8")
@@ -107,7 +109,7 @@ else()
 endif ()
 
 if (NOT BINARY)
-  if (X86_64 OR ARM64 OR POWER OR MIPS64 OR LOONGARCH64)
+  if (X86_64 OR ARM64 OR POWER OR MIPS64 OR LOONGARCH64 OR RISCV64)
     set(BINARY 64)
   else ()
     set(BINARY 32)