apply $cross_prefix before $cc is used

Originally committed as revision 5446 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -714,6 +714,11 @@ done
 # Combine FFLDFLAGS and the LDFLAGS environment variable
 LDFLAGS="$FFLDFLAGS $LDFLAGS"
 
+cc="${cross_prefix}${cc}"
+ar="${cross_prefix}${ar}"
+ranlib="${cross_prefix}${ranlib}"
+strip="${cross_prefix}${strip}"
+
 # we need to build at least one lib type
 if test "$lstatic" = "no" && test "$lshared" = "no" ; then
     cat <<EOF
@@ -989,11 +994,6 @@ fi
     if test "$force_libdir" != yes; then bindir="$prefix"; fi
 fi
 
-cc="${cross_prefix}${cc}"
-ar="${cross_prefix}${ar}"
-ranlib="${cross_prefix}${ranlib}"
-strip="${cross_prefix}${strip}"
-
 if test -z "$cross_prefix" ; then
 
 # ---