hurd: Add more GNU options support

Modules/Platform/GNU.cmake

@@ -9,6 +9,27 @@ set(CMAKE_SHARED_LIBRARY_RPATH_LINK_C_FLAG "-Wl,-rpath-link,")
 set(CMAKE_SHARED_LIBRARY_SONAME_C_FLAG "-Wl,-soname,")
 set(CMAKE_EXE_EXPORTS_C_FLAG "-Wl,--export-dynamic")
 
+# Shared libraries with no builtin soname may not be linked safely by
+# specifying the file path.
+set(CMAKE_PLATFORM_USES_PATH_WHEN_NO_SONAME 1)
+
+# Initialize C link type selection flags.  These flags are used when
+# building a shared library, shared module, or executable that links
+# to other libraries to select whether to use the static or shared
+# versions of the libraries.
+foreach(type SHARED_LIBRARY SHARED_MODULE EXE)
+  set(CMAKE_${type}_LINK_STATIC_C_FLAGS "-Wl,-Bstatic")
+  set(CMAKE_${type}_LINK_DYNAMIC_C_FLAGS "-Wl,-Bdynamic")
+endforeach()
+
+
+# Features for LINK_GROUP generator expression
+## RESCAN: request the linker to rescan static libraries until there is
+## no pending undefined symbols
+set(CMAKE_LINK_GROUP_USING_RESCAN "LINKER:--start-group" "LINKER:--end-group")
+set(CMAKE_LINK_GROUP_USING_RESCAN_SUPPORTED TRUE)
+
+
 # Debian policy requires that shared libraries be installed without
 # executable permission.  Fedora policy requires that shared libraries
 # be installed with the executable permission.  Since the native tools