devel/ocaml-opam: Fix build on armv7.

The LLVM assembler chokes on the assembly generated by the ARM32
backend of OCAML. Fixed by forcing binutils on ARM32.

The OCaml compiler generates text relocations on all of its supported
32 bits architectures, however the configure script only sets the -z
notext linker flag in the x86 case. This change makes sure that this
flag is used for the other architectures by setting LDFLAGS in the
environment of the configure script.

This commit may fix armv6 and powerpc as well, but this hasn't been
verified.

PR: 261180
MFH: 2024Q1
Reported by: fuz
Approved by: hannes@mehnert.org (maintainer)

(cherry picked from commit 84ef6c1c612525c29dd4c271ea4e91c2d54074af)