Add reproduction case for ocaml#4682

Signed-off-by: François Bobot <francois.bobot@cea.fr>

Author: bobot

test/blackbox-tests/test-cases/cmdline/profile.t/run.t

@@ -0,0 +1,19 @@
+# Bug #4632
+
+  $ dune build -p
+  dune build: option `-p' needs an argument
+  Usage: dune build [OPTION]... [TARGET]...
+  Try `dune build --help' or `dune --help' for more information.
+  [1]
+
+  $ dune build --root . --verbose 2>&1 | grep "; profile"
+   ; profile = Dev
+
+  $ dune build -p foo --verbose 2>&1 | grep "; profile"
+   ; profile = Release
+
+  $ DUNE_PROFILE="bar" dune build --root . --verbose 2>&1 | grep "; profile"
+   ; profile = User_defined "bar"
+
+  $ DUNE_PROFILE="bar" dune build -p foo --verbose 2>&1 | grep "; profile"
+   ; profile = User_defined "bar"