Updates to comply C99 and pass enable-stop-on-warning with pedantic
Compilation fails with clang16: sci_gateway/c/sci_getURL.c:43:5: error: call to undeclared function 'Sciwarning'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
Fixes also incompatible function pointer types errors.
Edited by Stéphane MOTTELET