Update search path for scp.exe.

This is to accommodate scp.exe's new location within the
git-2 tree.  This preferably would have gone in with the
previous CL but I forgot it.

Change-Id: Iba2067b6cef22bfefd4bc81e052008b6bc408495
diff --git a/scp.cmd b/scp.cmd
index fc5a6d8..314d72b 100644
--- a/scp.cmd
+++ b/scp.cmd
@@ -3,7 +3,7 @@

 @rem Get the abolute path to the Git installation root.

 @for /F "delims=" %%I in ("%~dp0.\git-*_bin") do @set git_install_root=%%~fI

-@set PATH=%git_install_root%\bin;%git_install_root%\mingw\bin;%PATH%

+@set PATH=%git_install_root%\bin;%git_install_root%\usr\bin;%git_install_root%\mingw\bin;%PATH%


 :: Set the HOME variable to depot_tools (the parent of this directory's parent).

 @if not exist "%HOME%" @for /F "delims=" %%I in ("%~dp0") do @set HOME=%%~fI