fuzzing: Add driver to run fuzz targets on a given list of files

This is enabled if the path to libFuzzer.a is not specified when running
the configure script.

fuzz/Makefile.am

@@ -1,12 +1,12 @@
-CPPFLAGS = @CPPFLAGS@ \
+AM_CPPFLAGS = @CPPFLAGS@ \
 	-I$(top_srcdir)/src/libstrongswan \
 	-DPLUGINDIR=\""$(abs_top_builddir)/src/libstrongswan/plugins\"" \
 	-DPLUGINS="\"${fuzz_plugins}\""
 
-LDFLAGS = @LDFLAGS@ ${libfuzzer} \
+fuzz_ldflags = ${libfuzzer} \
 	$(top_builddir)/src/libstrongswan/.libs/libstrongswan.a \
 	-Wl,-Bstatic -lgmp -Wl,-Bdynamic \
-	-stdlib=libc++ -lstdc++
+	@FUZZING_LDFLAGS@
 
 FUZZ_TARGETS=fuzz_certs
 
@@ -14,5 +14,9 @@ all-local: $(FUZZ_TARGETS)
 
 CLEANFILES=$(FUZZ_TARGETS)
 
-fuzz_certs: fuzz_certs.c
-	$(CC) $(CPPFLAGS) $(CFLAGS) -o $@ $< $(LDFLAGS)
+fuzz_certs: fuzz_certs.c ${libfuzzer}
+	$(CC) $(AM_CPPFLAGS) $(CFLAGS) -o $@ $< $(fuzz_ldflags)
+
+noinst_LIBRARIES = libFuzzerLocal.a
+libFuzzerLocal_a_SOURCES = libFuzzerLocal.c
+libFuzzerLocal_a_LIBADD = $(top_builddir)/src/libstrongswan/libstrongswan.la