Description: Use WTF_CPU_UNKNOWN when building for riscv64

WebKitGTK doesn't build on riscv64 even with the JIT disabled.
Treating the CPU as unknown is perhaps a bit severe, but it allows us
to get the build done until someone steps up to maintain this
properly.

Bug: https://bugs.webkit.org/show_bug.cgi?id=271371

Author: bertogg

Source/WTF/wtf/PlatformCPU.h

@@ -285,14 +285,6 @@
 
 #endif /* ARM */
 
-/* CPU(RISCV64) - RISC-V 64-bit */
-#if    defined(__riscv) \
-    && defined(__riscv_xlen) \
-    && (__riscv_xlen == 64)
-#define WTF_CPU_RISCV64 1
-#define WTF_CPU_KNOWN 1
-#endif
-
 #if !CPU(KNOWN)
 #define WTF_CPU_UNKNOWN 1
 #endif

Source/cmake/WebKitCommon.cmake

@@ -125,8 +125,6 @@ if (NOT HAS_RUN_WEBKIT_COMMON)
         set(WTF_CPU_PPC64 1)
     elseif (LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "ppc64le")
         set(WTF_CPU_PPC64LE 1)
-    elseif (LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "^riscv64")
-        set(WTF_CPU_RISCV64 1)
     elseif (LOWERCASE_CMAKE_SYSTEM_PROCESSOR MATCHES "^loongarch64")
         set(WTF_CPU_LOONGARCH64 1)
     else ()