Add initialization checking in BFGS, and replace the old BFGS with a new one in CG-BFGS.

[19hello]

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[Copilot]

Pull request overview

This PR updates the ionic relaxation flow to switch cg_bfgs into the newer/traditional BFGS implementation safely (by adding lazy initialization), and also modifies the OpenMPI stage1 build configuration.

Changes:

• Switch cg_bfgs -> bfgs handoff to select relax_method[1] = "1" (the BFGS/bfgs_trad path).
• Add lazy initialization (is_initialized) to BFGS so relax_step() can be called safely without a prior explicit allocate().
• Update the OpenMPI installer to pass explicit compiler selections to ./configure.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
toolchain/scripts/stage1/install_openmpi.sh	Forces compiler variables during OpenMPI configure (may affect toolchain portability).
source/source_relax/ions_move_cg.cpp	Changes the cg_bfgs threshold switch to select bfgs_trad (relax_method[1]="1").
source/source_relax/bfgs.h	Adds an is_initialized flag to support safe lazy initialization.
source/source_relax/bfgs.cpp	Lazily calls allocate() from relax_step() if needed.

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[mohanchen]

LGTM