grpc: Fix recipe to prepend to LD_LIBRARY_PATH rather than clobber

[nextsilicon-itay-bookstein]

In the presence of an ambient LD_LIBRARY_PATH we want to prepend rather than clobber, same as in the case of Mac. Otherwise we may end up missing library paths required by the user.

Summary

Changes to recipe: grpc

Motivation

Recipe modifies cmake in a way that invokes protoc with a modified LD_LIBRARY_PATH under Linux. However, rather than prepending, it assigns, causing build errors when LD_LIBRARY_PATH is necessary.

Details

The PR fixes the recipe to prepend to the existing environment variable.

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• Read the contributing guidelines
• Checked that this PR is not a duplicate: list of PRs by recipe
• Tested locally with at least one configuration using a recent version of Conan

[jcar87]

Hi @nextsilicon-itay-bookstein , thanks for opening this PR. We are currently in maintenance, but will get to this shortly.

I would imagine that this is something specific to your case, rather than something general? that is, you have en overridden LD_LIBRARY_PATH to support the system runtime (glibc, libstdc++, libm, pthread, etc), correct? Otherwise this should not cause errors

[nextsilicon-itay-bookstein]

Yes, for example easybuild/lmod foreign package manager, where loading packages sets this environment variable. Note that the Mac flow just a few lines beforehand does prepend instead of assign.

[nextsilicon-itay-bookstein]

Actually, upon further inspection, the Mac flow only propagates, doesn't preprend. Odd.

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 5 (9665f1d07952442e7ef87fdac1bbf8dd86e5439b):

• grpc/1.65.0:
  All packages built successfully! (All logs)

• grpc/1.54.3:
  All packages built successfully! (All logs)

• grpc/1.50.1:
  All packages built successfully! (All logs)

• grpc/1.50.0:
  All packages built successfully! (All logs)

---

Conan v2 pipeline ✔️

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All green in build 5 (9665f1d07952442e7ef87fdac1bbf8dd86e5439b):

• grpc/1.50.0:
  All packages built successfully! (All logs)

• grpc/1.54.3:
  All packages built successfully! (All logs)

• grpc/1.65.0:
  All packages built successfully! (All logs)

• grpc/1.50.1:
  All packages built successfully! (All logs)