Build only a single library type, static or shared

Typically, a static library should be more useful for UCDN. Use the
standard BUILD_SHARED_LIBS toggle of CMake to switch between the
library types, and link a static library by default.

If both library types are desired, they have to be built and installed
separately, but this should be a non-issue.

CMakeLists.txt

@@ -1,19 +1,19 @@
 cmake_minimum_required(VERSION 2.6)
 project(ucdn C)
 
-ADD_DEFINITIONS(-O2 -Wall -Werror -pedantic -std=c89)
+add_definitions(-O2 -Wall -Werror -pedantic -std=c89)
 
-add_library(ucdn_static STATIC ucdn.c ucdn.h)
-add_library(ucdn_shared SHARED ucdn.c ucdn.h)
-set_target_properties(ucdn_static PROPERTIES OUTPUT_NAME ucdn)
-set_target_properties(ucdn_shared PROPERTIES OUTPUT_NAME ucdn)
-set_target_properties(ucdn_shared PROPERTIES VERSION 1.0.0)
-set_target_properties(ucdn_shared PROPERTIES SOVERSION 1)
+add_library(ucdn ucdn.c ucdn.h)
+
+if(BUILD_SHARED_LIBS)
+    set_target_properties(ucdn PROPERTIES VERSION 1.0.0)
+    set_target_properties(ucdn PROPERTIES SOVERSION 1)
+endif()
 
 add_executable(ucdn-test ucdn-test.c)
-target_link_libraries(ucdn-test ucdn_static)
+target_link_libraries(ucdn-test ucdn)
 
-install(TARGETS ucdn_static ucdn_shared
+install(TARGETS ucdn
 	LIBRARY DESTINATION lib
 	ARCHIVE DESTINATION lib)
 install(FILES ucdn.h DESTINATION include)