Add missing WTF_USE_JSVALUE64 for riscv64

Signed-off-by: David Abdurachmanov <david.abdurachmanov@gmail.com>

webkit-qtwebkit-23-riscv64.patch

@@ -43,7 +43,7 @@ index e5f4362c..f175d09e 100644
      INCLUDEPATH += $$QT.core.sources/../3rdparty/ce-compat
      INCLUDEPATH += $$SOURCE_DIR/os-win32
 diff --git a/Source/WTF/wtf/Platform.h b/Source/WTF/wtf/Platform.h
-index 56c6f256..cdcc94c6 100644
+index 56c6f256..639063bb 100644
 --- a/Source/WTF/wtf/Platform.h
 +++ b/Source/WTF/wtf/Platform.h
 @@ -164,6 +164,11 @@
@@ -58,7 +58,17 @@ index 56c6f256..cdcc94c6 100644
  /* CPU(X86) - i386 / x86 32-bit */
  #if   defined(__i386__) \
      || defined(i386)     \
-@@ -932,7 +937,8 @@
+@@ -906,7 +911,8 @@
+     || CPU(S390X) \
+     || CPU(AARCH64) \
+     || CPU(MIPS64) \
+-    || CPU(PPC64)
++    || CPU(PPC64) \
++    || CPU(RISCV64)
+ #define WTF_USE_JSVALUE64 1
+ #else
+ #define WTF_USE_JSVALUE32_64 1
+@@ -932,7 +938,8 @@
      && (CPU(X86) || CPU(X86_64) || CPU(ARM) || CPU(MIPS)) \
      && (OS(DARWIN) || !COMPILER(GCC) || GCC_VERSION_AT_LEAST(4, 1, 0)) \
      && !OS(WINCE) \