Fix use of unsafe localtime() and portable gmtime_r()

[XVilka]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the documentation and the rizin book with the relevant information (if needed)

Detailed description

Some code was using thread-unsafe localtime(), some code was using non-portable gmtime_r(). I created own portable rz_gmtime_r() in analogy to existing rz_localtime_r() and used it instead. Also removed unnecessary inline function from the header.

Test plan

CI is green.

Closing issues

Might be related to #982 (comment)

[XVilka]

I noticed a strange bug recently, sometimes it happens on Alpine Linux like in this PR:

[XX] db/tools/rz_ax rz-ax -t "1234567890 GMT-1"
RZ_NOPLUGINS=1 rizin -escr.utf8=0 -escr.color=0 -escr.interactive=0 -N -Qc '!rz-ax -t "1234567890 GMT-1" | cut -d " " -f 1,2' =
-- stdout
--- expected
+++ actual
@@ -1,1 +1,1 @@
-Fri Feb
+Sat Jun

See https://github.com/rizinorg/rizin/pull/1481/checks?check_run_id=3369716223#step:8:3159

Sometimes it happens on Windows:

[XX] C:\projects\rizin\test\db\tools\rz_ax rz-ax -t "1234567890 GMT-1"
ANSICON=1 RZ_NOPLUGINS=1 rizin -escr.utf8=0 -escr.color=0 -escr.interactive=0 -N -Qc '!rz-ax -t "1234567890 GMT-1" | cut -d " " -f 1,2' =
-- stdout
--- expected
+++ actual
@@ -1,1 +1,1 @@
-Fri Feb
+Mon Aug
[**]              C:\projects\rizin\test\db\tools\rz_ax      379 OK         9 BR        1 XX        5 FX

(See https://ci.appveyor.com/project/rizinorg/rizin/builds/40439023/job/guyflnbj6rm6chrm#L3464 - it's another, unrelated branch).

Is someone has any clues - please let me know.

Note, that this PR should be merged anyway, even if those bugs aren't fixed - it already improves the portability and thread-safety.

[wargio]

timezone

[pelijah]

I just ignore these timezone related fails.

[XVilka]

Ideally, the time decoding commands/functions in Rizin should not depend on the timezone.

[ret2libc]

I usually ignore those errors as well. They happen all the time on my machine.