py/nlrx86,x64: Replace #define of defined() with portable macro usage.

Using gcc -Wpedantic will warn that #define of defined() is non-portable
and this patch fixes this.

py/nlrx64.c

@@ -34,7 +34,11 @@
 // x86-64 callee-save registers are:
 //  rbx, rbp, rsp, r12, r13, r14, r15
 
-#define NLR_OS_WINDOWS (defined(_WIN32) || defined(__CYGWIN__))
+#if defined(_WIN32) || defined(__CYGWIN__)
+#define NLR_OS_WINDOWS 1
+#else
+#define NLR_OS_WINDOWS 0
+#endif
 
 __attribute__((used)) unsigned int nlr_push_tail(nlr_buf_t *nlr);
 

py/nlrx86.c

@@ -35,7 +35,11 @@
 // For reference, x86 callee save regs are:
 //  ebx, esi, edi, ebp, esp, eip
 
-#define NLR_OS_WINDOWS (defined(_WIN32) || defined(__CYGWIN__))
+#if defined(_WIN32) || defined(__CYGWIN__)
+#define NLR_OS_WINDOWS 1
+#else
+#define NLR_OS_WINDOWS 0
+#endif
 
 #if NLR_OS_WINDOWS
 unsigned int nlr_push_tail(nlr_buf_t *nlr) asm("nlr_push_tail");