stdbit.h: fix compilation error of generic stdc_ functions

[michallenc]

Summary

Generic stdc_ functions use _Generic macro, but this requires the type specific functions stdc_*_uc, stdc_*_ul and so on to be functions, not just another macro definitions.

This commit fixes the issue by ensuring all type specific functions are static inline functions, not macro definitions.

Impact

Fixes the compilation error of stdc_leading_ones, stdc_trailing_ones, stdc_count_zeros, stdc_count_ones,
stdc_has_single_bit and stdc_bit_width functions.

Testing

Testing application is here. I will create a separate merge request for tests later.

Compile errors before the fix:

Create version.h
CC:  stdbit.c In file included from stdbit.c:31:
stdbit.c: In function ‘leading_ones’:
stdbit.c:207:14: error: ‘stdc_leading_ones_uc’ undeclared (first use in this function); did you mean ‘stdc_leading_zeros_uc’?
  207 |       ret2 = stdc_leading_ones(uc);
      |              ^~~~~~~~~~~~~~~~~
stdbit.c:207:14: note: each undeclared identifier is reported only once for each function it appears in
stdbit.c: In function ‘trailing_ones’:
stdbit.c:385:14: error: ‘stdc_trailing_ones_uc’ undeclared (first use in this function); did you mean ‘stdc_trailing_zeros_uc’?
  385 |       ret2 = stdc_trailing_ones(uc);
      |              ^~~~~~~~~~~~~~~~~~
stdbit.c: In function ‘count_zeros’:
stdbit.c:830:14: error: ‘stdc_count_zeros_uc’ undeclared (first use in this function); did you mean ‘stdc_leading_zeros_uc’?
  830 |       ret2 = stdc_count_zeros(uc);
      |              ^~~~~~~~~~~~~~~~
stdbit.c: In function ‘count_ones’:
stdbit.c:919:14: error: ‘stdc_count_ones_uc’ undeclared (first use in this function)
  919 |       ret2 = stdc_count_ones(uc);
      |              ^~~~~~~~~~~~~~~
stdbit.c: In function ‘has_single_bit’:
stdbit.c:1008:14: error: ‘stdc_has_single_bit_uc’ undeclared (first use in this function); did you mean ‘has_single_bit’?
 1008 |       ret2 = stdc_has_single_bit(uc);
      |              ^~~~~~~~~~~~~~~~~~~
stdbit.c: In function ‘bit_width’:
stdbit.c:1097:14: error: ‘stdc_bit_width_uc’ undeclared (first use in this function); did you mean ‘stdc_bit_ceil_uc’?
 1097 |       ret2 = stdc_bit_width(uc);
      |              ^~~~~~~~~~~~~~
make[2]: *** [/path/to/nuttx/apps/Application.mk:330: stdbit.c.home.michal.Michal.projects.nuttx.apps.testing.libc.stdbit.o] Error 1
make[1]: *** [Makefile:54: /path/to/nuttx/apps/testing/libc/stdbit_all] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [tools/LibTargets.mk:248: /path/to/nuttx/apps/libapps.a] Error 2
make: *** Waiting for unfinished jobs....

The application compiles and all tests pass after the fix.

[michallenc]

ping @jerpelea for 13.0 backport

[github-actions]

MemBrowse Memory Report

No memory changes detected for:

• arduino-mega2560
• esp32-devkitc
• hifive1-revb
• mirtoo
• qemu-armv8a
• qemu-intel64
• rx65n-rsk2mb
• s698pm-dkit
• stm32-nucleo-f103rb