Fix for not visible pthreads function with glibc 2.15

Linking error will appear:

Linking CXX executable ../../openmw
/usr/bin/ld: CMakeFiles/openmw.dir/__/__/components/bsa/bsa_archive.cpp.o: undefined reference to symbol 'pthread_mutexattr_settype@@GLIBC_2.2.5'
/usr/bin/ld: note: 'pthread_mutexattr_settype@@GLIBC_2.2.5' is defined in DSO /lib/libpthread.so.0 so try adding it to the linker command line
/lib/libpthread.so.0: could not read symbols: Invalid operation
collect2: ld returned 1 exit status

if we don't add explicitly pthreads library to linker flags
after update glibc to version 2.15 on (Arch) Linux.

Signed-off-by: Lukasz Gromanowski <lgromanowski@gmail.com>

CMakeLists.txt

@@ -186,6 +186,11 @@ endif (APPLE)
 
 # Dependencies
 
+# Fix for not visible pthreads functions for linker with glibc 2.15 
+if (UNIX AND NOT APPLE)
+find_package (Threads)
+endif()
+
 find_package(OGRE REQUIRED)
 find_package(Boost REQUIRED COMPONENTS system filesystem program_options thread)
 find_package(OIS REQUIRED)

apps/openmw/CMakeLists.txt

@@ -92,6 +92,11 @@ target_link_libraries(openmw
     MyGUIOgrePlatform
 )
 
+# Fix for not visible pthreads functions for linker with glibc 2.15 
+if (UNIX AND NOT APPLE)
+target_link_libraries(openmw ${CMAKE_THREAD_LIBS_INIT})
+endif()
+
 if(APPLE)
     find_library(CARBON_FRAMEWORK Carbon)
     target_link_libraries(openmw ${CARBON_FRAMEWORK})