1772575 - Build system should set the default @rpath for rust executables like http3server

Status: NEW

(Firefox Build System :: General, enhancement)

Description

[Haik Aftandilian [:haik]]

Note: rpath and executable_path refer to the @rpath and @executable_path dyld variables explained in the macOS dyld man page dyld(1).

This is a follow up cleanup-fix to bug 1770484 to change the build system so that http3server (and any other rust executables like it) will have a default dyld rpath (set to executable_path). i.e., make it so that http3server doesn't need a moz.build rpath setting and picks up the default from the build system.

Background: with the fix for bug 1770484, our Mac dylibs will be built with an install name dependent on the dyld variable @rpath instead of @executable_path. For example libnss3.dylib uses @rpath/libnss3.dylib and executables that link with libnss3.dylib need to have an rpath so that dyld knows how to resolve that path. Bug 1770484 changes rules.mk to set the default rpath to executable_path for all built executables. Executables needing a different rpath can add additional rpaths or override the rpath in their specific moz.build file. One test executable http3server wasn't covered by the changes and needs some build system expertise to be changed to not use moz.build.