SR-438: 'make distcheck' fails for libdispatch on Linux

Small fixes to (a) use proper paths to libpwq when building
out-of-tree and (b) include tests/linux_port.h in list of
test sources (needed for distcheck).  With these changes
'make distcheck' works as expected.

Signed-off-by: Daniel A. Steffen <[email protected]>

Author: dgrove-oss

src/Makefile.am

@@ -57,8 +57,8 @@ AM_CXXFLAGS=$(DISPATCH_CFLAGS) $(CXXBLOCKS_FLAGS)
 AM_OBJCXXFLAGS=$(DISPATCH_CFLAGS) $(CXXBLOCKS_FLAGS)
 
 if BUILD_OWN_PTHREAD_WORKQUEUES
-  PTHREAD_WORKQUEUE_LIBS=../libpwq/libpthread_workqueue.la
-  PTHREAD_WORKQUEUE_CFLAGS=-I../libpwq/include
+  PTHREAD_WORKQUEUE_LIBS=$(top_builddir)/libpwq/libpthread_workqueue.la
+  PTHREAD_WORKQUEUE_CFLAGS=-I$(top_srcdir)/libpwq/include
 else
   if HAVE_PTHREAD_WORKQUEUES
     PTHREAD_WORKQUEUE_LIBS=-lpthread_workqueue