Use bundled ocaml-csexp and ocaml-pp (RHEL only)

*On RHEL only* the aim is to minimize source packages.  Use the
bundled ocaml-csexp and ocaml-pp and remove those as build
dependencies.  They are still listed as Requires by some binary
packages that we don't actually use in RHEL.

ocaml-dune.spec

@@ -12,7 +12,7 @@
 
 Name:           ocaml-dune
 Version:        3.15.2
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        Composable build system for OCaml and Reason
 
 # Dune itself is MIT.  Some bundled libraries have a different license:
@@ -54,8 +54,10 @@ BuildRequires:  emacs-nw
 BuildRequires:  make
 BuildRequires:  ocaml >= 4.08
 BuildRequires:  ocaml-compiler-libs
+%if !0%{?rhel}
 BuildRequires:  ocaml-csexp-devel >= 1.5.0
 BuildRequires:  ocaml-pp-devel >= 1.2.0
+%endif
 BuildRequires:  ocaml-rpm-macros
 
 %if %{with docs}
@@ -490,8 +492,10 @@ sed -i 's/, < 6//'g doc/requirements.txt
 %endif
 
 # We also want the libraries
+%if !0%{?rhel}
 # Do not use the bundled csexp and pp when building them
 rm -fr vendor/{csexp,pp}
+%endif
 ./dune.exe build %{?_smp_mflags} --verbose --release @install
 
 %install
@@ -588,6 +592,9 @@ cd -
 %files -n ocaml-xdg-devel -f .ofiles-xdg-devel
 
 %changelog
+* Wed May 15 2024 Richard W.M. Jones <rjones@redhat.com> - 3.15.2-2
+- Use bundled ocaml-csexp and ocaml-pp (RHEL only)
+
 * Wed Apr 24 2024 Jerry James <loganjerry@gmail.com> - 3.15.2-1
 - Version 3.15.2