[cmake] add cmake building

cmake/FindNIX.cmake

@@ -0,0 +1,30 @@
+# - Try to find NIX
+# Once done this will define
+#  NIX_FOUND - System has Nix
+#  NIX_INCLUDE_DIRS - The Nix include directories
+#  NIX_LIBRARIES - The libraries needed to use Nix
+
+
+find_path(NIX_INCLUDE_DIR nix.hpp
+    HINTS $ENV{NIX_ROOT}/include
+    /usr/local/include
+    /usr/include
+    PATH_SUFFIXES nix)
+
+find_library(NIX_LIBRARY NAMES nix libnix
+  HINTS ${NIX_INCLUDE_DIR}/../lib
+  HINTS ${NIX_INCLUDE_DIR}/../build
+  /usr/local/lib
+  /usr/lib)
+
+set(NIX_LIBRARIES ${NIX_LIBRARY})
+set(NIX_INCLUDE_DIRS ${NIX_INCLUDE_DIR})
+
+include(FindPackageHandleStandardArgs)
+# handle the QUIETLY and REQUIRED arguments and set NIX_FOUND to TRUE
+# if all listed variables are TRUE
+find_package_handle_standard_args(Nix DEFAULT_MSG
+  NIX_LIBRARY NIX_INCLUDE_DIR)
+
+mark_as_advanced(NIX_INCLUDE_DIR NIX_LIBRARY)
+