ENH: Added CMAKE_SHARED_LIBRARY_SONAME_C_FLAG and CMAKE_SHARED_LIBRARY_SONAME_CXX_FLAG settings to enable shared library version support for SGI.

Modules/Platform/IRIX64.cmake

@@ -3,6 +3,8 @@ SET(CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS "-shared -rdata_shared")
 SET(CMAKE_SHARED_LIBRARY_CREATE_CXX_FLAGS "-shared -rdata_shared") 
 SET(CMAKE_SHARED_LIBRARY_RUNTIME_FLAG "-Wl,-rpath,")       # -rpath
 SET(CMAKE_SHARED_LIBRARY_RUNTIME_FLAG_SEP "")   # : or empty
+SET(CMAKE_SHARED_LIBRARY_SONAME_C_FLAG "-Wl,-soname,")
+SET(CMAKE_SHARED_LIBRARY_SONAME_CXX_FLAG "-Wl,-soname,")
 IF(NOT CMAKE_COMPILER_IS_GNUCXX)
   # Set default flags init.
   SET(CMAKE_C_FLAGS_INIT "")