Don't use mprotect on Cygwin

src/platform-posix.cc

Index: src/platform-posix.cc
diff --git a/src/platform-posix.cc b/src/platform-posix.cc
index 1ea53c83ea186a8807bb1152e2a75dde820c47e2..52cf02963a0580f2cd17d0aca5f2025b6cbe38a5 100644
--- a/src/platform-posix.cc
+++ b/src/platform-posix.cc
@@ -70,6 +70,7 @@ intptr_t OS::MaxVirtualMemory() {
 }
 
 
+#ifndef __CYGWIN__
 // Get rid of writable permission on code allocations.
 void OS::ProtectCode(void* address, const size_t size) {
   mprotect(address, size, PROT_READ | PROT_EXEC);
@@ -80,6 +81,7 @@ void OS::ProtectCode(void* address, const size_t size) {
 void OS::Guard(void* address, const size_t size) {
   mprotect(address, size, PROT_NONE);
 }
+#endif  // __CYGWIN__
 
 
 // ----------------------------------------------------------------------------