[Patch] Use internal pthreads reimplementation only when building with MSVC

Hi

The following patch, which we added to build mingw-postgresql on Fedora,
makes the internal minimal pthreads reimplementation only used when
building with MSVC, as on MINGW it causes symbol collisions with the
symbols provided my winpthreads.

Thanks
Sandro

diff -rupN postgresql-11.5/src/interfaces/ecpg/ecpglib/misc.c
postgresql-11.5-new/src/interfaces/ecpg/ecpglib/misc.c
--- postgresql-11.5/src/interfaces/ecpg/ecpglib/misc.c 2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/ecpg/ecpglib/misc.c 2020-04-08
11:20:39.850738296 +0200
@@ -449,7 +449,7 @@ ECPGis_noind_null(enum ECPGttype type, c
     return false;
 }

-#ifdef WIN32
+#ifdef _MSC_VER
 #ifdef ENABLE_THREAD_SAFETY

 void
diff -rupN
postgresql-11.5/src/interfaces/ecpg/include/ecpg-pthread-win32.h
postgresql-11.5-new/src/interfaces/ecpg/include/ecpg-pthread-win32.h
--- postgresql-11.5/src/interfaces/ecpg/include/ecpg-pthread-win32.h
2019-08-05 23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/ecpg/include/ecpg-pthread-win32.h
2020-04-08 11:20:39.851738296 +0200
@@ -7,7 +7,7 @@

 #ifdef ENABLE_THREAD_SAFETY

-#ifndef WIN32
+#ifndef _MSC_VER

 #include <pthread.h>
 #else
diff -rupN postgresql-11.5/src/interfaces/libpq/fe-connect.c
postgresql-11.5-new/src/interfaces/libpq/fe-connect.c
--- postgresql-11.5/src/interfaces/libpq/fe-connect.c 2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/libpq/fe-connect.c 2020-04-08
11:20:39.853738297 +0200
@@ -50,7 +50,7 @@
 #endif

 #ifdef ENABLE_THREAD_SAFETY
-#ifdef WIN32
+#ifdef _MSC_VER
 #include "pthread-win32.h"
 #else
 #include <pthread.h>
diff -rupN postgresql-11.5/src/interfaces/libpq/fe-secure.c
postgresql-11.5-new/src/interfaces/libpq/fe-secure.c
--- postgresql-11.5/src/interfaces/libpq/fe-secure.c    2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/libpq/fe-secure.c 2020-04-08
11:20:39.854738297 +0200
@@ -48,7 +48,7 @@
 #include <sys/stat.h>

 #ifdef ENABLE_THREAD_SAFETY
-#ifdef WIN32
+#ifdef _MSC_VER
 #include "pthread-win32.h"
 #else
 #include <pthread.h>
diff -rupN postgresql-11.5/src/interfaces/libpq/fe-secure-openssl.c
postgresql-11.5-new/src/interfaces/libpq/fe-secure-openssl.c
--- postgresql-11.5/src/interfaces/libpq/fe-secure-openssl.c 2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/libpq/fe-secure-openssl.c
2020-04-08 11:20:39.855738298 +0200
@@ -47,7 +47,7 @@
 #include <sys/stat.h>

 #ifdef ENABLE_THREAD_SAFETY
-#ifdef WIN32
+#ifdef _MSC_VER
 #include "pthread-win32.h"
 #else
 #include <pthread.h>
diff -rupN postgresql-11.5/src/interfaces/libpq/libpq-int.h
postgresql-11.5-new/src/interfaces/libpq/libpq-int.h
--- postgresql-11.5/src/interfaces/libpq/libpq-int.h    2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/libpq/libpq-int.h 2020-04-08
11:20:39.855738298 +0200
@@ -29,7 +29,7 @@
 #endif

 #ifdef ENABLE_THREAD_SAFETY
-#ifdef WIN32
+#ifdef _MSC_VER
 #include "pthread-win32.h"
 #else
 #include <pthread.h>
diff -rupN postgresql-11.5/src/interfaces/libpq/pthread-win32.c
postgresql-11.5-new/src/interfaces/libpq/pthread-win32.c
--- postgresql-11.5/src/interfaces/libpq/pthread-win32.c 2019-08-05
23:14:59.000000000 +0200
+++ postgresql-11.5-new/src/interfaces/libpq/pthread-win32.c 2020-04-08
11:21:51.674766968 +0200
@@ -10,10 +10,13 @@
 *-------------------------------------------------------------------------
 */

+#ifdef _MSC_VER
+
 #include "postgres_fe.h"

 #include "pthread-win32.h"

+
 DWORD
 pthread_self(void)
 {
@@ -58,3 +61,5 @@ pthread_mutex_unlock(pthread_mutex_t *mp
     LeaveCriticalSection(*mp);
     return 0;
 }
+
+#endif // _MSC_VER