kc3-lang/libevent

2022-06-23T13:38:14

build: only try silence options if they exist Otherwise GCC will warn. i.e: ```bash CCLD libevent_openssl.la cc1: note: unrecognized command-line option ‘-Wno-void-pointer-to-enum-cast’ may have been intended to silence earlier diagnostics CCLD libevent_mbedtls.la ```