I had to make a small patch to get gst-plugins to compile with gcc-2.95.3:

--- gst-plugins-0.6.4/gst/level/filter.func     2003-10-05
16:46:21.000000000 +0
000
+++ gst-plugins-0.6.4-mod/gst/level/filter.func 2003-11-29
08:33:30.000000000 +0
000
@@ -9,10 +9,11 @@
   double squaresum = 0.0;      /* square sum of the integer samples */
   register double square = 0.0;                /* Square */
   register double PSS = 0.0;           /* Peak Square Sample */
+  gdouble normalizer;
 
   *CS = 0.0;      /* Cumulative Square for this block */
 
-  gdouble normalizer = (double) (1 << resolution);
+  normalizer = (double) (1 << resolution);
 
   /*
    * process data here