gdaldrivermanager.cpp: Do not look for plugins in GetRealDriver when GDAL_NO_AUTOLOAD set.

[schwehr]

Fixes #11332

What does this PR do?

In GDALPluginDriverProxy::GetRealDriver(), return a nullptr if GDAL_NO_AUTOLOAD is set and plugins are not available. This avoids the call the CPLGetSymbol.

In custom builds like my bazel build, this lets me completely remove CPLGetSymbol from the build. When GDAL runs in a sandbox, it is helpful to not even have a chance for this function to run. Any call to CPLGetSymbol would cause the sandbox to trigger a violation and kill the work.

What are related issues/pull requests?

#11332

Environment

Provide environment details, if relevant:

• OS: Custom linux with bazel build
• Compiler: llvm

Note: Failure that I can't tell if it's related to the change I made. The most recent commits on head fail too, but it's luck on which one.

Executing transaction: ...working... done
+ test -f /home/runner/miniconda3/envs/test/conda-bld/libgdal-core_1732816510057/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_pl/lib/gdalplugins/gdal_PDF.so
+ gdalinfo --format PDF
ERROR 1: libpoppler.so.140: cannot open shared object file: No such file or directory
ERROR 1: libpoppler.so.140: cannot open shared object file: No such file or directory
+ ./test_pdf.sh
++ dirname ./test_pdf.sh
+ pushd ./test_data/
+ gdalinfo test_iso32000.pdf
ERROR 1: libpoppler.so.140: cannot open shared object file: No such file or directory
ERROR 1: libpoppler.so.140: cannot open shared object file: No such file or directory
gdalinfo failed - unable to open 'test_iso32000.pdf'. Did you intend to call ogrinfo?
WARNING: Tests failed for libgdal-pdf-3.10.0-hb578332_2112.tar.bz2 - moving package to /home/runner/miniconda3/envs/test/conda-bld/broken
Traceback (most recent call last):
export PREFIX=/home/runner/miniconda3/envs/test/conda-bld/libgdal-core_1732816510057/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_pl

[coveralls]

coverage: 74.174% (+0.002%) from 74.172%
when pulling ccfa017 on schwehr:11332-exclude-cplgetsymbol-without-plugins
into 02c5966 on OSGeo:master.