Merge branch 'ci_lld' into 'develop'

.gitlab-ci.yml

CI/ubuntu-18.04-gcc-shark.cmake

CI/ubuntu-18.04-llvm-shark.cmake

CI/ubuntu-18.04-llvm.cmake

Modules/Adapters/OSSIMAdapters/src/otbDEMHandler.cxx

Modules/Adapters/OSSIMAdapters/src/otbRPCSolverAdapter.cxx

.../Adapters/OSSIMAdapters/test/otbOssimElevManagerTest2.cxx

.../Adapters/OSSIMAdapters/test/otbOssimElevManagerTest4.cxx

...s/OSSIMAdapters/test/otbOssimJpegFileResourceLeakTest.cxx

Modules/Core/Transform/test/otbCreateProjectionWithOSSIM.cxx

Modules/ThirdParty/Ossim/include/otb_ossim.h

...es/ThirdParty/OssimPlugins/include/ossimPluginConstants.h

...les/ThirdParty/OssimPlugins/src/ossim/ossimPluginCommon.h

...rdParty/OssimPlugins/src/ossim/ossimRadarSat2TiffReader.h

...s/ThirdParty/OssimPlugins/src/ossim/ossimSentinel1Model.h

...irdParty/OssimPlugins/src/ossim/ossimTerraSarProductDoc.h

...irdParty/OssimPlugins/src/ossim/ossimTerraSarTiffReader.h