warpx: add libs attribute to fix build on aarch64 (#22072)

Co-authored-by: Axel Huebl <axel.huebl@plasma.ninja>

var/spack/repos/builtin/packages/warpx/package.py

@@ -93,6 +93,7 @@ def cmake_args(self):
         args = [
             '-DBUILD_SHARED_LIBS:BOOL={0}'.format(
                 'ON' if '+shared' in spec else 'OFF'),
+            '-DCMAKE_INSTALL_LIBDIR=lib',
             # variants
             '-DWarpX_APP:BOOL={0}'.format(
                 'ON' if '+app' in spec else 'OFF'),
@@ -123,3 +124,12 @@ def cmake_args(self):
         ]
 
         return args
+
+    @property
+    def libs(self):
+        libsuffix = {'2': '2d', '3': '3d', 'rz': 'rz'}
+        dims = self.spec.variants['dims'].value
+        return find_libraries(
+            ['libwarpx.' + libsuffix[dims]], root=self.prefix, recursive=True,
+            shared=True
+        )