libjpeg-turbo: Fix Darwin lib install name (#39834)

* Fix Darwin lib install name in var/spack/repos/builtin/packages/libjpeg-turbo/package.py

* Update var/spack/repos/builtin/packages/libjpeg-turbo/package.py

Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>

---------

Co-authored-by: Tamara Dahlgren <35777542+tldahlgren@users.noreply.github.com>

var/spack/repos/builtin/packages/libjpeg-turbo/package.py

@@ -88,3 +88,9 @@ def cmake_args(self):
         ]
 
         return args
+
+    @run_after("install")
+    def darwin_fix(self):
+        # The shared library is not installed correctly on Darwin; fix this
+        if self.spec.satisfies("platform=darwin") and ("+shared" in self.spec):
+            fix_darwin_install_name(self.prefix.lib)