Add include directory for internal libltdl

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit dfd680030c)

CMakeLists.txt

@@ -153,10 +153,12 @@ endif( NO_BUILTIN )
 
 ##### system checks #############################
 
+tde_save_and_set( CMAKE_REQUIRED_INCLUDES ${CMAKE_SOURCE_DIR}/libltdl )
 check_include_file( "ltdl.h" HAVE_LTDL_H )
 if( NOT HAVE_LTDL_H )
-  tde_message_fatal( "ltdl.h are required, but not found on your system" )
+  tde_message_fatal( "ltdl.h is required, but not found on your system" )
 endif( )
+tde_restore( CMAKE_REQUIRED_INCLUDES )
 
 check_include_file( "alloca.h" HAVE_ALLOCA_H )
 check_include_file( "arpa/nameser8_compat.h" HAVE_ARPA_NAMESER8_COMPAT_H )

tdeinit/CMakeLists.txt

@@ -17,6 +17,7 @@ include_directories(
   ${CMAKE_BINARY_DIR}/tdecore
   ${CMAKE_SOURCE_DIR}
   ${CMAKE_SOURCE_DIR}/dcop
+  ${CMAKE_SOURCE_DIR}/libltdl
   ${CMAKE_SOURCE_DIR}/tdecore
   ${CMAKE_SOURCE_DIR}/tdeui
   ${CMAKE_SOURCE_DIR}/tdeio

tdeio/tdeio/CMakeLists.txt

@@ -18,6 +18,7 @@ include_directories(
   ${CMAKE_BINARY_DIR}/tdecore
   ${CMAKE_SOURCE_DIR}
   ${CMAKE_SOURCE_DIR}/dcop
+  ${CMAKE_SOURCE_DIR}/libltdl
   ${CMAKE_SOURCE_DIR}/tdecore
   ${CMAKE_SOURCE_DIR}/tdecore/network
   ${CMAKE_SOURCE_DIR}/tdeui