bst_vs_heap_vs_hashmap: configurable seed, make code a bit nicer

README.adoc

@@ -11111,8 +11111,12 @@ It has been used to answer:
 To benchmark on the host, we do:
 
 ....
-./build-userland-in-tree --force-rebuild --optimization-level 3 ./userland/cpp/bst_vs_heap_vs_hashmap.cpp
-./userland/cpp/bst_vs_heap_vs_hashmap.out 10000000 10000 | tee bst_vs_heap_vs_hashmap.dat
+./build-userland-in-tree \
+  --force-rebuild \
+  --optimization-level 3 \
+  ./userland/cpp/bst_vs_heap_vs_hashmap.cpp \
+;
+./userland/cpp/bst_vs_heap_vs_hashmap.out 10000000 10000 0 | tee bst_vs_heap_vs_hashmap.dat
 gnuplot \
   -e 'input_noext="bst_vs_heap_vs_hashmap"' \
   -e 'heap_zoom_max=50' \
@@ -11139,7 +11143,7 @@ To benchmark on gem5, we first build the benchmark with <<m5ops-instructions>> e
   --emulator gem5 \
   --static \
   --userland userland/cpp/bst_vs_heap_vs_hashmap.cpp \
-  --userland-args='100000' \
+  --userland-args='100000 1 0' \
   -- \
   --cpu-type=DerivO3CPU \
   --caches \