The file we are patching looks like this:

```
$ cat mkspecs/qconfig.pri
#configuration
CONFIG +=  shared qpa no_mocdepend release qt_framework
host_build {
    QT_ARCH = x86_64
    QT_TARGET_ARCH = x86_64
} else {
    QT_ARCH = x86_64
    QMAKE_DEFAULT_LIBDIRS = /lib /usr/lib
    QMAKE_DEFAULT_INCDIRS = /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1 /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/c++/4.2.1/backward /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/5.1/include /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include
}
QT_CONFIG +=  minimal-config small-config medium-config large-config full-config fontconfig xrender c++11 accessibility opengl shared qpa reduce_exports getaddrinfo ipv6ifname getifaddrs png system-freetype no-harfbuzz system-zlib nis cups iconv openssl rpath corewlan concurrent audio-backend release qt_framework

#versioning
QT_VERSION = 5.3.0
QT_MAJOR_VERSION = 5
QT_MINOR_VERSION = 3
QT_PATCH_VERSION = 0

#namespaces
QT_LIBINFIX =
QT_NAMESPACE =

# pkgconfig
PKG_CONFIG_SYSROOT_DIR =
PKG_CONFIG_LIBDIR = /usr/lib/pkgconfig:/usr/local/Library/ENV/pkgconfig/10.9

QT_APPLE_CLANG_MAJOR_VERSION = 5
QT_APPLE_CLANG_MINOR_VERSION = 1
```

We are removing the 4 lines (inluding an empty one) referring to pkg-config. With that, the file looks as if qt `./configure` was called without `PKG_CONFIG_LIBDIR` set. I don't think `PKG_CONFIG_SYSROOT_DIR` will be ever set given that this is executed in superenv. I think it's still best to remove it.