TST: use linker flags instead of install_rpath to set the RPATH

meson-python does not support `install_rpath` yet and anyhow `install_rpath`
is not exposed in the introspection data and thus cannot be set by
meson-python when building the Python wheel. Use `link_args` to set the RPATH.

Author: dnicolodi

tests/packages/sharedlib-in-package/mypkg/meson.build

@@ -8,7 +8,11 @@ py.extension_module(
     dependencies: lib_dep,
     install: true,
     subdir: 'mypkg',
-    install_rpath: '$ORIGIN',
+    # install_rpath is not exposed in the Meson introspection data in Meson
+    # versions prior to 1.6.0 and thus cannot be set by meson-python when
+    # building the Python wheel. Use link_args to set the RPATH.
+    # install_rpath: '$ORIGIN',
+    link_args: '-Wl,-rpath,$ORIGIN',
 )
 
 py.install_sources(

tests/packages/sharedlib-in-package/src/meson.build

@@ -30,7 +30,11 @@ lib = shared_library(
     c_args: export_dll_args,
     install: true,
     install_dir: py.get_install_dir() / 'mypkg',
-    install_rpath: '$ORIGIN/sub',
+    # install_rpath is not exposed in the Meson introspection data in Meson
+    # versions prior to 1.6.0 and thus cannot be set by meson-python when
+    # building the Python wheel. Use link_args to set the RPATH.
+    # install_rpath: '$ORIGIN/sub',
+    link_args: '-Wl,-rpath,$ORIGIN/sub',
 )
 
 lib_dep = declare_dependency(