Useless extra symlinks installed for shared libs

[jwakely]

At some point after boost 1.69.0 every shared library also acquired useless symlinks on linux:

libboost_system.so.1.73.0
libboost_system.so.1.73
libboost_system.so.1
libboost_system.so

The first file is needed (it's the actual shared library) and the last one is needed (it's the symlink that is used when you link with -lboost_system) but the second and third are useless.

Creating those extra symlinks is done by installed-shared-lib-generator in tools/build/src/tools/stage.jam and is controlled by <install-no-version-symlinks>on. That used to be set in boostcpp.jam but that was removed in https://github.com/boostorg/boost/commit/47ef674f752ad2cfeb581665cbea18ee6faecd2e#diff-09cc8a80ee9a61cf35f9c4498eefd67a

https://github.com/boostorg/headers/commit/8fb634067e4cddbf932299f8cfdc9c8049a44d3f appears to be setting that elsewhere now, but it doesn't seem to work.

[stale[bot]]

Thank you for your contributions. Main development of B2 has moved to https://github.com/bfgroup/b2 This issue has been automatically marked as "transition" to indicate the potential for needing transition to the new B2 development project.