wsd: make: build the fuzzer binaries only configured with fuzzing

This reduces the build time significantly while also
minimizing the disk-space requirements for builds.

When configured with --enable-fuzzers the fuzzing
target binaries are built.

Change-Id: Ia8560d876f548d04ac085503e55a3a5dca90f590
Signed-off-by: Ashod Nakashian <ashod.nakashian@collabora.co.uk>

Makefile.am

@@ -187,6 +187,8 @@ coolwsd_fuzzer_SOURCES = $(coolwsd_sources) \
                          $(shared_sources) \
                          kit/DummyLibreOfficeKit.cpp
 
+if ENABLE_LIBFUZZER
+
 admin_fuzzer_CPPFLAGS = \
 			-DKIT_IN_PROCESS=1 \
 			$(AM_CPPFLAGS)
@@ -217,6 +219,8 @@ httpresponse_fuzzer_SOURCES = \
 			       fuzzer/HttpResponse.cpp
 httpresponse_fuzzer_LDFLAGS = -fsanitize=fuzzer $(AM_LDFLAGS)
 
+endif # ENABLE_LIBFUZZER
+
 clientnb_SOURCES = net/clientnb.cpp \
                    common/DummyTraceEventEmitter.cpp \
                    common/Log.cpp \