fuzz: Add fuzzing boilerplate

fuzz/Makefile.am

@@ -0,0 +1,12 @@
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/src/libstrongswan \
+	-DPLUGINDIR=\""$(abs_top_builddir)/src/libstrongswan/plugins\"" \
+	-DPLUGINS="\"${fuzz_plugins}\""
+
+noinst_PROGRAMS = fuzz_certs
+
+fuzz_certs_SOURCES = fuzz_certs.c
+
+fuzz_certs_LDFLAGS = libFuzzer.a -lstdc++
+
+fuzz_certs_LDADD = $(top_builddir)/src/libstrongswan/libstrongswan.la