MDEV-8743: use mkostemp when available with O_CLOEXEC

Closes #639

cmake/os/WindowsCache.cmake

@@ -100,6 +100,7 @@ SET(HAVE_MEMCPY 1 CACHE  INTERNAL "")
 SET(HAVE_MEMMOVE 1 CACHE  INTERNAL "")
 SET(HAVE_MEMORY_H 1 CACHE  INTERNAL "")
 SET(HAVE_MKSTEMP CACHE  INTERNAL "")
+SET(HAVE_MKOSTEMP CACHE  INTERNAL "")
 SET(HAVE_MLOCK CACHE  INTERNAL "")
 SET(HAVE_MLOCKALL CACHE  INTERNAL "")
 SET(HAVE_MMAP CACHE  INTERNAL "")

config.h.cmake

@@ -181,6 +181,7 @@
 #cmakedefine HAVE_MEMCPY 1
 #cmakedefine HAVE_MEMMOVE 1
 #cmakedefine HAVE_MKSTEMP 1
+#cmakedefine HAVE_MKOSTEMP 1
 #cmakedefine HAVE_MLOCKALL 1
 #cmakedefine HAVE_MMAP 1
 #cmakedefine HAVE_MMAP64 1

configure.cmake

@@ -370,6 +370,7 @@ CHECK_FUNCTION_EXISTS (mallinfo HAVE_MALLINFO)
 CHECK_FUNCTION_EXISTS (memcpy HAVE_MEMCPY)
 CHECK_FUNCTION_EXISTS (memmove HAVE_MEMMOVE)
 CHECK_FUNCTION_EXISTS (mkstemp HAVE_MKSTEMP)
+CHECK_FUNCTION_EXISTS (mkostemp HAVE_MKOSTEMP)
 CHECK_FUNCTION_EXISTS (mlock HAVE_MLOCK)
 CHECK_FUNCTION_EXISTS (mlockall HAVE_MLOCKALL)
 CHECK_FUNCTION_EXISTS (mmap HAVE_MMAP)

mysys/mf_tempfile.c

@@ -22,7 +22,9 @@
 #include <paths.h>
 #endif
 
-
+#ifdef HAVE_MKOSTEMP
+#define mkstemp(A) mkostemp(A, O_CLOEXEC)
+#endif
 
 /*
   @brief