run: add --userland-args to make userland arguments across QEMU and gem5

Get rid of --userland-before as a consequence.

README.adoc

@@ -2914,11 +2914,17 @@ First let's run a dynamically linked executable built with the Buildroot toolcha
 ./run \
   --arch aarch64 \
   --userland print_argv \
-  -- \
-  asdf qwer \
+  --userland-args 'asdf "qw er"' \
 ;
 ....
 
+Output:
+
+....
+asdf
+qw er
+....
+
 This runs link:userland/print_argv.c[]. `--userland` path resolution is analogous to <<baremetal-setup-getting-started,that of `./run --baremetal`>>.
 
 `./build-userland` is further documented at: <<userland-directory>>.
@@ -2939,8 +2945,7 @@ You can also try statically linked executables with:
   --arch aarch64 \
   --userland-build-id static \
   --userland print_argv \
-  -- \
-  asdf qwer \
+  --userland-args 'asdf "qw er"' \
 ;
 ....
 
@@ -2957,14 +2962,13 @@ Or you can run statically linked built by the host packaged toolchain with:
   --arch aarch64 \
   --userland-build-id host-static \
   --userland print_argv \
-  -- \
-  asdf qwer \
+  --userland-args 'asdf "qw er"' \
 ;
 ....
 
 TODO expose dynamically linked executables built by the host toolchain. It also works, we just have to use e.g. `-L /usr/aarch64-linux-gnu`, so it's not really hard, I'm just lazy.
 
-==== QEMU user mode GDB
+==== User mode GDB
 
 It's nice when <<gdb,the obvious>> just works, right?
 
@@ -2972,9 +2976,8 @@ It's nice when <<gdb,the obvious>> just works, right?
 ./run \
   --arch aarch64 \
   --userland print_argv \
+  --userland-args 'asdf "qw er"' \
   --wait-gdb \
-  -- \
-  asdf qwer \
 ;
 ....
 
@@ -2993,11 +2996,10 @@ Or alternatively, if you are using <<tmux>>, do everything in one go with:
 ....
 ./run \
   --arch aarch64 \
-  --userland print_argv \
   --tmux-args main \
+  --userland print_argv \
+  --userland-args 'asdf "qw er"' \
   --wait-gdb \
-  -- \
-  asdf qwer \
 ;
 ....
 
@@ -3035,28 +3037,25 @@ So let's just play with some static ones:
   --arch aarch64 \
   --gem5 \
   --userland print_argv \
-  --userland-build-id static \
-  -- \
-  --options 'asdf "qw er"' \
+  --userland-args 'asdf "qw er"' \
 ;
 ....
 
-TODO: how to escape spaces?
+TODO: how to escape spaces on the command line arguments?
 
 Step debug also works:
 
 ....
 ./run \
-  --arch arm \
-  --wait-gdb \
+  --arch aarch64 \
   --gem5 \
   --userland print_argv \
+  --userland-args 'asdf "qw er"' \
   --userland-build-id static \
-  -- \
-  --options 'asdf "qw er"' \
+  --wait-gdb \
 ;
 ./run-gdb \
-  --arch arm \
+  --arch aarch64 \
   --gem5 \
   --userland print_argv \
   --userland-build-id static \
@@ -3108,10 +3107,8 @@ time \
   ./run \
   --arch arm \
   --gem5 \
-  --userland \
-  "$(./getvar --arch arm buildroot_build_build_dir)/dhrystone-2/dhrystone" \
-  -- \
-  --options 100000 \
+  --userland "$(./getvar --arch arm buildroot_build_build_dir)/dhrystone-2/dhrystone" \
+  --userland-args 'asdf qwer' \
 ;
 ....