build: Enabling ability to use precompiled headers and some other build fixes

Change-Id: If2b216e5674fc762338929026733f3dcb801bb1b
Refs: #1588
diff --git a/tests/wscript b/tests/wscript
index be93c0a..7d8c36d 100644
--- a/tests/wscript
+++ b/tests/wscript
@@ -44,6 +44,7 @@
             use='core-objects unit-tests-main',
             includes='.',
             install_path=None,
+            pch='test-pch.hpp',
           )
 
         # NFD tests
@@ -57,6 +58,7 @@
             use='daemon-objects unit-tests-main',
             includes='.',
             install_path=None,
+            pch='test-pch.hpp',
           )
 
         if bld.env['HAVE_LIBPCAP']:
@@ -75,6 +77,7 @@
             use='rib-objects unit-tests-main',
             includes=['.'],
             install_path=None,
+            pch='test-pch.hpp',
           )
 
     # Other tests (e.g., stress tests that can be enabled even if unit tests are disabled)