mk-build-deps failes when control file is in path containing spaces

[Ｖ字龍(Vdragon)]

## Console output
```
~/Workspace/Programming/My_projects/Vubuntu/Patches/安裝與設定各桌面環境/桌面環境通用設定（若可行的話）/鍵盤快捷鍵設定/按下 Windows 鍵開啟選單/KDE/安裝 ksuperkey % LANGUAGE=en mk-build-deps ksuperkey.control
cp: target ‘ksuperkey/equivs.cx3DoH’ is not a directory
Error on copy of the template files: exit status 1
~/Workspace/Programming/My_projects/Vubuntu/Patches/安裝與設定各桌面環境/桌面環境通用設定（若可行的話）/鍵盤快捷鍵設定/按下 Windows 鍵開啟選單/KDE/安裝 ksuperkey %
```

AFAICS the bug is at /usr/bin/equivs-build script that "builddir" string is not properly quoted.
```
system("cp -R /usr/share/equivs/template/* $builddir") == 0 or
   die "Error on copy of the template files: exit status " . ($?>>8) . "\n";
```

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: devscripts 2.14.1
ProcVersionSignature: Ubuntu 3.16.0-24.32-lowlatency 3.16.4
Uname: Linux 3.16.0-24-lowlatency i686
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: i386
CurrentDesktop: KDE
Date: Sun Nov 23 22:54:13 2014
InstallationDate: Installed on 2013-03-08 (624 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release i386 (20121017.2)
SourcePackage: devscripts
UpgradeStatus: Upgraded to trusty on 2014-04-19 (218 days ago)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.