this script generates forbuild.mk.  it takes config.mk and adds a "_FOR_BUILD"
suffix to every variable it finds in there.  but it only matches vars that are
all uppercase and miss things like "libdir".  normally this isn't a problem as
the vars have the same value.  but when you cross-compile, this script will
produce a different config.mk file which will have different paths (such as
config.mk:libdir=/usr/lib64 but forbuild.mk:libdir=/usr/lib).  so update the
script to convert all vars including lowercase ones.

Patch by Peter Nilsson Lundblad

--- a/mk4build
+++ b/mk4build
@@ -106,7 +106,7 @@
 
 sedScript="${outputName}.${sedExtension}"
 sed -n -e '
-s/^ *\([A-Z][A-Z_]*\) *=.*$/\1/
+s/^ *\([[:alpha:]][[:alpha:]_]*\) *=.*$/\1/
 t found
 d
 :found