fix some gcc warnings (#73) * tweak string size fix gcc8 warnings ``` svr-agentfwd.c: In function 'bindagent': svr-agentfwd.c:254:53: warning: '%s' directive output may be truncated writing up to 107 bytes into a region of size between 0 and 107 [-Wformat-truncation=] snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s", path, sockfile); ^~ ~~~~~~~~ svr-agentfwd.c:254:2: note: 'snprintf' output between 2 and 216 bytes into a destination of size 108 snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s", path, sockfile); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ``` * cleanup signed/unsigned comparison fix gcc8 warnings ``` scp.c: In function 'do_local_cmd': scp.c:132:17: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] for (i = 0; i < a->num; i++) ^ scpmisc.c: In function 'addargs': scpmisc.c:161:25: warning: comparison of integer expressions of different signedness: 'int' and 'u_int' {aka 'unsigned int'} [-Wsign-compare] } else if (args->num+2 >= nalloc) ^~ scpmisc.c: In function 'replacearg': scpmisc.c:183:12: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] if (which >= args->num) ^~ scpmisc.c: In function 'freeargs': scpmisc.c:196:17: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] for (i = 0; i < args->num; i++) ^ ``` see https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/misc.h.diff?r1=1.16&r2=1.17

-----BEGIN DSA PRIVATE KEY-----
MIIBuwIBAAKBgQDFCjdRXKvWGNWicL1Kb2tK+eE5lQ8rmTh9mmTWTLWWetztrKis
xhtlWt7bAGElGhgs7qEHkGJeTRIxkMcDIfoJ57Fz146v2/2/s++t0aEqA23nBpJK
hSr/egFmUx/qxmdBhFrAbO1i+cJiYgWk+kigZuw1yagR/rmBq+6+Mba/zwIVAKpb
1/TlBiQT5Yg1ygDHpjVxYZTFAoGAO5Lk/1kpFQsImVp78q0UQFVvoEf/kJmzRLPU
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c0cDiLRk2bm4T/HJNLv5c2b1fC4R/sMx5gg4WWeB621BJ9cNdK+gNQIVAJk25eTp
+yi+kfUGX+jJNbP12B/F
-----END DSA PRIVATE KEY-----