cmake - add option for fuzzing

Signed-off-by: Ralph Giles <giles@thaumas.net>

CMakeLists.txt

@@ -63,6 +63,10 @@ set(OPUS_HARDENING_HELP_STR "run-time checks that are cheap and safe for use in
 option(OPUS_HARDENING ${OPUS_HARDENING_HELP_STR} ON)
 add_feature_info(OPUS_HARDENING OPUS_HARDENING ${OPUS_HARDENING_HELP_STR})
 
+set(OPUS_FUZZING_HELP_STR "causes the encoder to make random decisions (do not use in production).")
+option(OPUS_FUZZING ${OPUS_FUZZING_HELP_STR} OFF)
+add_feature_info(OPUS_FUZZING OPUS_FUZZING ${OPUS_FUZZING_HELP_STR})
+
 set(OPUS_INSTALL_PKG_CONFIG_MODULE_HELP_STR "install pkg-config module.")
 option(OPUS_INSTALL_PKG_CONFIG_MODULE ${OPUS_INSTALL_PKG_CONFIG_MODULE_HELP_STR} ON)
 add_feature_info(OPUS_INSTALL_PKG_CONFIG_MODULE OPUS_INSTALL_PKG_CONFIG_MODULE ${OPUS_INSTALL_PKG_CONFIG_MODULE_HELP_STR})
@@ -281,6 +285,10 @@ if(OPUS_HARDENING)
   target_compile_definitions(opus PRIVATE ENABLE_HARDENING)
 endif()
 
+if(OPUS_FUZZING)
+  target_compile_definitions(opus PRIVATE FUZZING)
+endif()
+
 if(OPUS_VAR_ARRAYS)
   target_compile_definitions(opus PRIVATE VAR_ARRAYS)
 elseif(OPUS_USE_ALLOCA)