Installing boost-spirit "properly"

Boost-spirit is not a self-contained library by any means,
unfortunately. Rather than inventing ad-hoc measures of installing the
dependencies and dependencies of dependencies and..., let's stop playing
whack-a-mole and instead use the big installation hammer.

We're not calling `b2 install` because that one attempts to build these
libraries. We do not want that. On the other hand, `b2 headers` is
"lazy" as it prefers to create symlinks where it makes sense. These
symlinks are relative, pointing to the source directory of each
individual Boost module -- hence that `cp`.

Yay for custom build systems, once again :(.

Change-Id: Iad867386ac5907630db8bdde0668d8fd9edee580
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8986d4f..83634a6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -45,13 +45,14 @@
 
 find_package(docopt REQUIRED)
 find_package(spdlog REQUIRED)
+find_package(Boost REQUIRED)
 
 set(netconf-cli_SRCS
     src/main.cpp
     )
 
 add_executable(netconf-cli ${netconf-cli_SRCS})
-target_link_libraries(netconf-cli docopt)
+target_link_libraries(netconf-cli docopt Boost::boost)
 add_dependencies(netconf-cli target-NETCONF_CLI_VERSION)
 target_include_directories(netconf-cli PRIVATE ${PROJECT_BINARY_DIR})