meson: adjust nlohmann-json dependency

Simplify the nlohmann-json dependency in meson and use the wrap file
location aligned with other repos.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I3c157966fafb5d9090c3c67d916b06932d3ef3df
diff --git a/meson.build b/meson.build
index 5a7efd4..5bbdfc2 100644
--- a/meson.build
+++ b/meson.build
@@ -8,15 +8,6 @@
     meson_version: '>=1.1.1',
 )
 
-cpp = meson.get_compiler('cpp')
-
-if cpp.has_header('nlohmann/json.hpp')
-    nlohmann_json = declare_dependency()
-else
-    subproject('nlohmann-json')
-    nlohmann_json = dependency('nlohmann_json')
-endif
-
 executable(
     'health-monitor',
     [
@@ -27,7 +18,7 @@
         dependency('phosphor-logging'),
         dependency('sdbusplus'),
         dependency('sdeventplus'),
-        nlohmann_json,
+        dependency('nlohmann_json', include_type: 'system')
     ],
     install: true,
     install_dir: get_option('bindir')