[linux] remove absolute rpath of /usr/lib/swift/linux added to many shared libraries

This was presumably added as a backup, in case the libraries in a toolchain
couldn't be found, but will not work well, so take it out.

Author: finagolfin

cmake/modules/AddSwift.cmake

@@ -461,7 +461,7 @@ function(add_swift_host_library name)
       INSTALL_NAME_DIR "@rpath")
   elseif(SWIFT_HOST_VARIANT_SDK STREQUAL LINUX)
     set_target_properties(${name} PROPERTIES
-      INSTALL_RPATH "$ORIGIN:/usr/lib/swift/linux")
+      INSTALL_RPATH "$ORIGIN")
   elseif(SWIFT_HOST_VARIANT_SDK STREQUAL CYGWIN)
     set_target_properties(${name} PROPERTIES
       INSTALL_RPATH "$ORIGIN:/usr/lib/swift/cygwin")

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -998,7 +998,7 @@ function(_add_swift_target_library_single target name)
   elseif("${SWIFTLIB_SINGLE_SDK}" STREQUAL "LINUX")
     set_target_properties("${target}"
       PROPERTIES
-      INSTALL_RPATH "$ORIGIN:/usr/lib/swift/linux")
+      INSTALL_RPATH "$ORIGIN")
   elseif("${SWIFTLIB_SINGLE_SDK}" STREQUAL "CYGWIN")
     set_target_properties("${target}"
       PROPERTIES

tools/SourceKit/cmake/modules/AddSwiftSourceKit.cmake

@@ -99,7 +99,7 @@ macro(add_sourcekit_library name)
   if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
     if(SOURCEKITLIB_SHARED)
       set_target_properties(${name} PROPERTIES BUILD_WITH_INSTALL_RPATH TRUE)
-      set_target_properties(${name} PROPERTIES INSTALL_RPATH "$ORIGIN/../lib/swift/linux:/usr/lib/swift/linux")
+      set_target_properties(${name} PROPERTIES INSTALL_RPATH "$ORIGIN/../lib/swift/linux")
     endif()
   endif()