cmake: Add CMakeRC module and ::rc namespace

This module allows to add binary files into UHD (e.g., for cal data
storage) in a platform-independent way.

The upstream CMakeRC.cmake is modified in the following way to allow
linkage against a shared object:

```diff
     # Generate the actual static library. Each source file is just a single file
     # with a character array compiled in containing the contents of the
     # corresponding resource file.
     add_library(${name} STATIC ${libcpp})
     set_property(TARGET ${name} PROPERTY CMRC_LIBDIR "${libdir}")
     set_property(TARGET ${name} PROPERTY CMRC_NAMESPACE "${ARG_NAMESPACE}")
     target_link_libraries(${name} PUBLIC cmrc::base)
     set_property(TARGET ${name} PROPERTY CMRC_IS_RESOURCE_LIBRARY TRUE)
+    set_property(TARGET ${name} PROPERTY POSITION_INDEPENDENT_CODE ON)
```

This forces the -fPIC flag for the static object that CMakeRC generates,
allowing to link it into a shared object file.

The version of CMakeRC used is: a7e355290, cloned from
git@github.com:vector-of-bool/cmrc.git.

1 files changed, 6 insertions, 1 deletions

diff --git a/host/lib/CMakeLists.txt b/host/lib/CMakeLists.txt
index 18bc47f54..4d747c9c7 100644
--- a/host/lib/CMakeLists.txt
+++ b/host/lib/CMakeLists.txt
@@ -131,6 +131,11 @@ if(ENABLE_C_API)
 endif(ENABLE_C_API)
 
 ########################################################################
+# Add common resource compiler subdirectory
+########################################################################
+add_subdirectory(rc)
+
+########################################################################
 # Add DLL resource file to Windows build
 ########################################################################
 if(MSVC)
@@ -172,7 +177,7 @@ if(ENABLE_MPMD)
     list(APPEND libuhd_sources $<TARGET_OBJECTS:uhd_rpclib>)
 endif()
 add_library(uhd SHARED ${libuhd_sources})
-target_link_libraries(uhd ${Boost_LIBRARIES} ${libuhd_libs})
+target_link_libraries(uhd ${Boost_LIBRARIES} ${libuhd_libs} uhd_rc)
 set_target_properties(uhd PROPERTIES DEFINE_SYMBOL "UHD_DLL_EXPORTS")
 if(NOT LIBUHDDEV_PKG)
     set_target_properties(uhd PROPERTIES SOVERSION "${UHD_ABI_VERSION}")