JIT: update epilog exit size assert for x86 (dotnet/coreclr#25302)

With the advent of dotnet/coreclr#25251 we can now see the epilog exit sequence on x86 vary
by as much as 6 bytes. Update the assert accordingly.

Fixes dotnet/coreclr#25301.

Commit migrated from dotnet/coreclr@e31c78b

src/coreclr/src/jit/emit.cpp

@@ -2059,9 +2059,10 @@ void emitter::emitEndFnEpilog()
         // underestimation of the epilog size is harmless (since the EIP
         // can not be between instructions).
         assert(emitEpilogCnt == 1 ||
-               (emitExitSeqSize - newSize) <= 5 // delta between size of various forms of jmp (size is either 6 or 5)
+               (emitExitSeqSize - newSize) <= 6 // delta between size of various forms of jmp (size is either 6 or 5,
+                                                // or a 5 byte mov plus 2 byte jmp)
                                                 // and various forms of ret (size is either 1 or 3). The combination can
-                                                // be anything been 1 and 5.
+                                                // be anything between 1 and 6.
                );
         emitExitSeqSize = newSize;
     }