DOC: remove hotfix patch from backporting/Mint howto

this patch is no longer required; we lowered the
version dependencies in the package proper

doc/technical/howto/backporting.txt

@@ -116,20 +116,6 @@ dpkg-buildpackage
 git clone git://git.lumiera.org/LUMIERA
 cd LUMIERA
 
-patch -p1 << EOF
---- lumiera-0.pre.03.orig/admin/scons/Platform.py
-+++ lumiera-0.pre.03/admin/scons/Platform.py
-@@ -120,7 +120,7 @@ def configure(env):
-     if not conf.CheckPkgConfig('cairomm-1.0', 0.6):
-         problems.append('Unable to configure Cairo--')
-     
--    verGDL   = '3.12'
-+    verGDL   = '3.8' # NOTE: lowered requriements here (was originally '3.12')
-     verGDLmm = '3.7.3'
-     urlGDLmm = 'http://ftp.gnome.org/pub/GNOME/sources/gdlmm/'
-     urlGDLmmDEB = 'http://lumiera.org/debian/'
-EOF
-
 scons CC=gcc-4.9 CXX=g++-4.9
 ----
 +