build: Add a test suite infrastructure

Makefile.am

@@ -1,6 +1,6 @@
 ## Process this file with automake to produce Makefile.in
 
-SUBDIRS = include man src
+SUBDIRS = include man src test
 
 ACLOCAL_AMFLAGS = -I m4
 

configure.ac

@@ -45,6 +45,7 @@ AC_CONFIG_FILES([
 	src/Makefile
 	src/libbsd.pc
 	src/libbsd-overlay.pc
+	test/Makefile
 ])
 AC_CONFIG_HEADERS([config.h])
 AC_OUTPUT

test/Makefile.am

@@ -0,0 +1,16 @@
+## Process this file with automake to produce Makefile.in
+
+# Set default values for user variables
+CFLAGS = -Wall -Wextra -Wno-unused-variable -Wno-unused-parameter
+
+AM_CPPFLAGS = \
+	-I$(top_builddir) \
+	-isystem $(top_srcdir)/include/bsd/ \
+	-include $(top_builddir)/config.h \
+	-DLIBBSD_OVERLAY -DLIBBSD_DISABLE_DEPRECATED \
+	-D__REENTRANT
+
+check_PROGRAMS = \
+	$(nil)
+
+TESTS = $(check_PROGRAMS)