loguru: fix preprocessor definition values

[mologie]

Loguru expects 0 or 1, but the recipe would set "False"/"True", which C's preprocessor would always evaluate to false.

Specify library name and version: loguru/*

PR #14543 added loguru, but improperly sets its preprocessor options. It sets the strings "False" or "True" as preprocessor definition due to quirks with how options are embedded. C's preprocessor evaluates both to false, so essentially all options are always off.

This PR sets 0 or 1 instead, so options can actually be toggled.

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[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 2 (ac64960633022f2d8db30e116b35c60bea7e2598):

• loguru/cci.20230406@:
  All packages built successfully! (All logs)

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Conan v2 pipeline ✔️

Note: Conan v2 builds may be required once they are on the v2 ready list

All green in build 2 (ac64960633022f2d8db30e116b35c60bea7e2598):

• loguru/cci.20230406@:
  All packages built successfully! (All logs)