Fix pthread reference in example CMakeLists.txt + removal of executable (SolidWallOfCode#82)

* cmake was generating -lpthread at beginning of compiler call, resulting
  in a undefined pthread_create
* added *.pc to .gitignore
* added example executables to .gitignore
* removed executable from repo

Author: keesspoelstra

.gitignore

@@ -4,6 +4,9 @@
 *.swp
 *.cbp
 
+# Pkg-config files
+*.pc
+
 # Compiled Dynamic libraries
 *.so
 *.dylib
@@ -17,7 +20,10 @@
 *.exe
 *.out
 *.app
+example/ex_diskstats
 example/ex_flat_space
+example/ex_host_file
+example/ex_lru_cache
 example/ex_netcompact
 example/ex_netdb
 unit_tests/test_libswoc

example/CMakeLists.txt

@@ -30,14 +30,18 @@ endif()
 
 add_executable(ex_lru_cache ex_lru_cache.cc)
 target_link_libraries(ex_lru_cache PUBLIC libswoc-static)
+
+set(THREADS_PREFER_PTHREAD_FLAG ON) # Without this flag CMake may resort to just '-lpthread'
+find_package(Threads)
+
 if (CMAKE_COMPILER_IS_GNUCXX)
     target_compile_options(ex_lru_cache PRIVATE -Wall -Wextra -Werror)
-    target_link_options(ex_lru_cache PRIVATE -lpthread)
+    target_link_libraries(ex_lru_cache PRIVATE Threads::Threads)
 endif()
 
 add_executable(ex_host_file ex_host_file.cc)
 target_link_libraries(ex_host_file PUBLIC libswoc-static)
 if (CMAKE_COMPILER_IS_GNUCXX)
     target_compile_options(ex_host_file PRIVATE -Wall -Wextra -Werror)
-    target_link_options(ex_host_file PRIVATE -lpthread)
+    target_link_libraries(ex_host_file PRIVATE Threads::Threads)
 endif()