Add back localtime.c implementation for MinGW

src/CMakeLists.txt

@@ -122,6 +122,11 @@ set( LIBEXIV2_PRIVATE_SRC
     helper_functions.cpp
 )
 
+if(MINGW)	
+    set(LIBEXIV2_PRIVATE_SRC ${LIBEXIV2_PRIVATE_SRC} localtime.c)	
+endif()
+
+
 # Private headers only needed to build the library
 set( LIBEXIV2_PRIVATE_HDR
     canonmn_int.hpp

src/timegm.h

@@ -5,8 +5,21 @@
 #pragma once
 #include <time.h>
 
+#ifdef  __cplusplus	
+extern "C" {	
+#endif
+
 // The UTC version of mktime
 /* timegm is replaced with _mkgmtime on Windows (msvc && mingw) */
-#if defined(__MINGW__) || defined(_MSC_VER)
+#if defined(_MSC_VER)
 #define timegm _mkgmtime
 #endif
+
+#if defined(__MINGW__)
+time_t timegm(struct tm * const tmp);
+#endif
+
+#ifdef  __cplusplus	
+}	
+#endif
+