[sr-dev] new master branch compiler warnings (Debian Buster)

[Juha Heinanen]

C (gcc) [M outbound.so]		outbound_mod.o
outbound_mod.c: In function 'mod_init':
outbound_mod.c:112:25: warning: pointer targets in passing argument 1 of 'SHA1' differ in signedness [-Wpointer-sign]
   SHA1(flow_token_secret.s, flow_token_secret.len, ob_key.s);
        ~~~~~~~~~~~~~~~~~^~
In file included from outbound_mod.c:28:
/usr/include/openssl/sha.h:44:16: note: expected 'const unsigned char *' but argument is of type 'char *'
 unsigned char *SHA1(const unsigned char *d, size_t n, unsigned char *md);
                ^~~~
outbound_mod.c:112:58: warning: pointer targets in passing argument 3 of 'SHA1' differ in signedness [-Wpointer-sign]
   SHA1(flow_token_secret.s, flow_token_secret.len, ob_key.s);
                                                    ~~~~~~^~
In file included from outbound_mod.c:28:
/usr/include/openssl/sha.h:44:16: note: expected 'unsigned char *' but argument is of type 'char *'
 unsigned char *SHA1(const unsigned char *d, size_t n, unsigned char *md);
                ^~~~