fix build of gta plugin when pkg-config is used

+ update related variable for build without pkg-config

Tested during cross-compilation for MS Windows using MinGW.

CMakeModules/FindGTA.cmake

@@ -33,7 +33,7 @@ IF(NOT GTA_FOUND)
         /usr/freeware/include
     )
     
-    FIND_LIBRARY(GTA_LIBRARY
+    FIND_LIBRARY(GTA_LIBRARIES
         NAMES gta libgta
         PATHS
         $ENV{GTA_DIR}/lib
@@ -50,8 +50,8 @@ IF(NOT GTA_FOUND)
     )
     
     SET(GTA_FOUND "NO")
-    IF(GTA_LIBRARY AND GTA_INCLUDE_DIRS)
+    IF(GTA_LIBRARIES AND GTA_INCLUDE_DIRS)
         SET(GTA_FOUND "YES")
-    ENDIF(GTA_LIBRARY AND GTA_INCLUDE_DIRS)
+    ENDIF(GTA_LIBRARIES AND GTA_INCLUDE_DIRS)
 
 ENDIF(NOT GTA_FOUND)

src/osgPlugins/gta/CMakeLists.txt

@@ -2,7 +2,7 @@ INCLUDE_DIRECTORIES( ${GTA_INCLUDE_DIRS} )
 
 SET(TARGET_SRC ReaderWriterGTA.cpp )
 
-SET(TARGET_LIBRARIES_VARS GTA_LIBRARY)
+SET(TARGET_LIBRARIES_VARS GTA_LIBRARIES)
 
 #### end var setup  ###
 SETUP_PLUGIN(gta)