support for macos

[i-infra]

Tested on aarch64 macos, need to test on x86_64 ubuntu still, but should be fine. Fixes some lint, moves some variables from stack to heap, and fixes libcurl init. Throws bus error on attempted decode without these patches.

[Guenael]

Hi,
Why do you believe this patch is necessary, and how, precisely, will it be beneficial?

-   for (uint32_t i = 0; i < samples_count; i += 8) {
+   for (uint32_t i = 0; i + 7 < samples_count; i += 8) {

[i-infra]

Hi, Why do you believe this patch is necessary, and how, precisely, will it be beneficial?

-   for (uint32_t i = 0; i < samples_count; i += 8) {
+   for (uint32_t i = 0; i + 7 < samples_count; i += 8) {

If the rtl_sdr returns a sequence of data that's not a multiple of 8, ie transfer is interrupted & partial buffer submitted, the following buffer manipulations could out-of-bounds index. This just guards against the case that samples_count % 8 != 0 which was flagged by building on MacOS. Can add a comment, or move to a different commit if you'd like!

Also, forgot that I had this PR open - sorry for the delay, and sorry for the other commits - I'd like to at least ensure upstream builds cleanly on MacOS, so please let me know if you'd like me to re-open the PR with just the MacOS fixes cherry-picked, as the debug logging for decodes on this branch as well as the rename from ".iq" to ".cu8" and ".cf32" are independently useful but not related to this PR.