Add support for m68000.

Thanks to Andreas Schwab.
diff --git a/src/utils.h b/src/utils.h
index 886017d..d8e03d4 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -63,6 +63,8 @@
     defined(_MIPS_ARCH_MIPS32R2) || \
     defined(__AARCH64EL__)
 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+#elif defined(__mc68000__)
+#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
 #elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
 #if defined(_WIN32)
 // Windows uses a 64bit wide floating point stack.