Fix typo which prevents expansion of libdir in pkgconfig files

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 93f89df..2fb8716 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -284,7 +284,7 @@
 file(RELATIVE_PATH pc_relative_bindir ${CMAKE_INSTALL_PREFIX} ${CMAKE_INSTALL_FULL_BINDIR})
 set(bindir "\${prefix}/${pc_relative_bindir}")
 file(RELATIVE_PATH pc_relative_libdir ${CMAKE_INSTALL_PREFIX} ${CMAKE_INSTALL_FULL_LIBDIR})
-set(libdir "\${prefix)/${pc_relative_libdir}")
+set(libdir "\${prefix}/${pc_relative_libdir}")
 file(RELATIVE_PATH pc_relative_includedir ${CMAKE_INSTALL_PREFIX} ${CMAKE_INSTALL_FULL_INCLUDEDIR})
 set(includedir "\${prefix}/${pc_relative_includedir}")
 if(CMAKE_SYSTEM_NAME MATCHES BSD)