[winasan] Update GetInstructionSize for Win10 1803

In Windows version 1803, the first instruction of ntdll!strchr is:
8a01 mov al,byte ptr [rcx]

This is the only needed change for this version as far as I can tell.

Differential Revision: https://reviews.llvm.org/D46458

llvm-svn: 332095

compiler-rt/lib/interception/interception_win.cc

@@ -453,6 +453,7 @@ static size_t GetInstructionSize(uptr address, size_t* rel_offset = nullptr) {
   }
 
   switch (*(u16*)(address)) {
+    case 0x018A:  // 8A 01 : mov al, byte ptr [ecx]
     case 0xFF8B:  // 8B FF : mov edi, edi
     case 0xEC8B:  // 8B EC : mov ebp, esp
     case 0xc889:  // 89 C8 : mov eax, ecx