Updating CMake to get GDAL working again on OS X.

modules/imgcodecs/CMakeLists.txt

@@ -51,6 +51,7 @@ if(HAVE_OPENEXR)
 endif()
 
 if(HAVE_GDAL)
+  add_definitions(-DHAVE_GDAL)
   include_directories(SYSTEM ${GDAL_INCLUDE_DIR})
   list(APPEND GRFMT_LIBS ${GDAL_LIBRARY})
 endif()

modules/imgcodecs/src/grfmt_gdal.cpp

@@ -38,6 +38,7 @@
 // the use of this software, even if advised of the possibility of such damage.
 //
 //M*/
+#include "precomp.hpp"
 #include "grfmt_gdal.hpp"
 
 #ifdef HAVE_GDAL