llvm-ld: add support of deps with the specific version (like liblzma.so.1.0.0)"

lib/Linker/Linker.cpp

 //===- lib/Linker/Linker.cpp - Basic Linker functionality  ----------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains basic Linker functionality that all usages will need.
@@ skipping 123 matching lines @@
     return FullPath;
 
   // Try the libX.so (or .dylib) form
   FullPath.eraseSuffix();
   FullPath.appendSuffix(sys::Path::GetDLLSuffix());
   if (FullPath.isDynamicLibrary())  // Native shared library?
     return FullPath;
   if (FullPath.isBitcodeFile())    // .so file containing bitcode?
     return FullPath;
 
+  // Try libX form, to make it possible to add dependency on the
+  // specific version of .so, like liblzma.so.1.0.0
+  FullPath.eraseSuffix();
+  if (FullPath.isDynamicLibrary())  // Native shared library?
+    return FullPath;
+  if (FullPath.isBitcodeFile())    // .so file containing bitcode?
+    return FullPath;
+
   // Not found .. fall through
 
   // Indicate that the library was not found in the directory.
   FullPath.clear();
   return FullPath;
 }
 
 /// FindLib - Try to convert Filename into the name of a file that we can open,
 /// if it does not already name a file we can open, by first trying to open
 /// Filename, then libFilename.[suffix] for each of a set of several common
@@ skipping 11 matching lines @@
   // Iterate over the directories in Paths to see if we can find the library
   // there.
   for (unsigned Index = 0; Index != LibPaths.size(); ++Index) {
     sys::Path Directory(LibPaths[Index]);
     sys::Path FullPath = IsLibrary(Filename, Directory);
     if (!FullPath.isEmpty())
       return FullPath;
   }
   return sys::Path();
 }