re PR d/91339 (libphobos: ftbfs when the path contains '~')

PR d/91339
d/dmd: Merge upstream dmd b37a537d3

Fixes the error: cannot find source code for runtime library file
'object.d' when the path contains '~'.

Reviewed-on: https://github.com/dlang/dmd/pull/10309

From-SVN: r274771

gcc/d/dmd/MERGE

@@ -1,4 +1,4 @@
-375ed10aa7eb28755f92775ca5c5399550cd100b
+b37a537d36c2ac69afa505a3110e2328c9fc0114
 
 The first line of this file holds the git revision number of the last
 merge done from the dlang/dmd repository.

gcc/d/dmd/root/filename.c

@@ -110,7 +110,8 @@ Strings *FileName::splitPath(const char *path)
                     case '~':
                     {
                         char *home = getenv("HOME");
-                        if (home)
+                        // Expand ~ only if it is prefixing the rest of the path.
+                        if (!buf.offset && p[1] == '/' && home)
                             buf.writestring(home);
                         else
                             buf.writestring("~");