Revert "qt: Default to build in-place and preserve the src"

This reverts commit 9b5f26f358d0f21323ca2eeb5399b73651c347aa.

Formula/qt.rb

@@ -78,16 +78,11 @@ class Qt < Formula
       args << '-arch' << 'x86'
     end
 
-    # We move the source and build in-place because:
-    # - Debug symbols need to find the source so build in the prefix
-    # - to fix https://github.com/mxcl/homebrew/issues/20020
-    # - PySide `make apidoc` needs the src
-    (prefix/"src").mkdir
-    mv Dir['*'], "#{prefix}/src/"
-    cd "#{prefix}/src"
-
     if build.with? 'debug-and-release'
       args << "-debug-and-release"
+      # Debug symbols need to find the source so build in the prefix
+      mv "../qt-everywhere-opensource-src-#{version}", "#{prefix}/src"
+      cd "#{prefix}/src"
     else
       args << "-release"
     end