sensors: Align source structure away from anti-patterns

The anti-patterns document comments on source structure, specifically
on placing internal headers in a parallel subtree[1]. dbus-sensors is an
example of violating this anti-pattern, so fix it.

[1]: https://github.com/openbmc/docs/blob/master/anti-patterns.md#placing-internal-headers-in-a-parallel-subtree

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I50ecaddd53fa9c9b7a0441af9de5e60bd94e47c6
diff --git a/tests/meson.build b/tests/meson.build
index 51d5d60..008ba19 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -34,7 +34,7 @@
         'test_HwmonTempSensor.cpp',
         dependencies: ut_deps_list,
         implicit_include_directories: false,
-        include_directories: '../include',
+        include_directories: '../src',
     )
 )
 
@@ -45,7 +45,7 @@
         'test_TachSensor.cpp',
         dependencies: ut_deps_list,
         implicit_include_directories: false,
-        include_directories: '../include',
+        include_directories: '../src',
     )
 )
 endif
@@ -58,6 +58,6 @@
         '../src/Utils.cpp',
         dependencies: ut_deps_list,
         implicit_include_directories: false,
-        include_directories: '../include',
+        include_directories: '../src',
     )
 )