cosmetics: Split all path variables into their own list.

Originally committed as revision 13637 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -783,22 +783,27 @@ CMDLINE_SELECT="
     static
     stripping
 "
-CMDLINE_SET='
-    arch
+
+PATHS_LIST='
     bindir
-    build_suffix
-    cc
-    cpu
-    cross_prefix
     incdir
     libdir
-    logfile
     mandir
     prefix
     shlibdir
+'
+
+CMDLINE_SET="
+    $PATHS_LIST
+    arch
+    build_suffix
+    cc
+    cpu
+    cross_prefix
+    logfile
     source_path
     target_os
-'
+"
 
 # code dependency declarations