clients & tests: Unify multiple definitions of x*alloc and related functions

Direct fail_on_null calls now produce output like:

    [weston-info] clients/weston-info.c:714: out of memory

xmalloc, et al produce output on failure like:

    [weston-info] out of memory (-1)

Signed-off-by: Bryce Harrington <bryce@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/Makefile.am b/Makefile.am
index 318a837..d1644ac 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -999,7 +999,9 @@
 	shared/file-util.h			\
 	shared/helpers.h			\
 	shared/os-compatibility.c		\
-	shared/os-compatibility.h
+	shared/os-compatibility.h		\
+	shared/xalloc.c			\
+	shared/xalloc.h
 
 libshared_cairo_la_CFLAGS =			\
 	-DDATADIR='"$(datadir)"'		\