implicit declaration of function ‘strncasecmp’ on gcc15

[andreasstieger]

With gcc15:

[    4s] gcc -Wall -Wextra -std=c99 -fPIC -DOPENSSL_LOAD_CONF -shared -o libsigv4.so sigv4.c -lssl -lcrypto
[    4s] sigv4.c: In function ‘get_signed_headers’:
[    4s] sigv4.c:243:9: error: implicit declaration of function ‘strncasecmp’; did you mean ‘strncmp’? [-Wimplicit-function-declaration]
[    4s]   243 |     if (strncasecmp(sigv4_params->headers[i].key.data, "x-amz-content-sha256", sigv4_params->headers[i].key.len) == 0)
[    4s]       |         ^~~~~~~~~~~
[    4s]       |         strncmp
[

You'll need #include <strings.h>...