[GIT PULL liburing] Add musl build-test for GitHub Action Bot

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

Hi Jens,

Please pull this musl build-test for GitHub action.

Several build issues have been reported by musl libc users when
compiling liburing. These are not isolated incidents, common
problems include:

  1) Missing system headers like <error.h>:
```
    timestamp.c:2:10: fatal error: error.h: No such file or directory
        2 | #include <error.h>
          |          ^~~~~~~~~
    compilation terminated.
```

  2) Undefined types like `cpu_set_t` and `loff_t`, which are available
     under glibc but missing without proper feature macros on musl:
```
    error: unknown type name 'cpu_set_t'
    error: unknown type name 'loff_t'; did you mean 'off_t'
```

These issues are musl-specific and have already led to numerous
commits fixing them, for example:

  e83246aca576 ("t/timestamp: Remove `#include <error.h>` and move `#include <time.h>` to the top")
  afffc0964a90 ("examples/zcrx: remove error.h")
  40cd129ec72c ("ooo-file-unreg.c: Include poll.h instead of sys/poll.h")
  ff0bc26d3220 ("test: Drop including error.h header")
  9485c21f8f36 ("liburing.pc.in: add -D_GNU_SOuRCE to Cflags")
  0fbcc44fe1fb ("examples,test: Remove unused linux/errqueue.h")
  0a9e2268e2a8 ("examples: Use t_error instead of glibc's error.")
  3b0b4976d7da ("test: Use t_error instead of glibc's error.")
  11dc64a71558 ("Add custom error function for tests.")
  45969ce39dc7 ("configure: fix compile-checks for statx")
  c34070e08199 ("liburing.h: define GNU_SOURCE for cpu_set_t")
  43b7ec8d1788 ("build: add -D_GNU_SOURCE to all CPPFLAGS/CFLAGS.")
  1cf969dfcba7 ("examples: disable ucontext-cp if ucontext.h is not available")
  bbf591c6c2d7 ("fix missing '#include <sys/stat.h>' in 'src/include/liburing.h")
  8171778c835b ("fix build on musl libc")

Despite these fixes, the CI pipeline currently only tests against
glibc-based environments. To catch musl regressions early and ensure
broader compatibility, add Alpine Linux (musl libc) build-test to
the CI.

The following changes since commit 9a0461dc82e894aca53246e589b7d6cb880de103:

  test/send_recv: properly return T_EXIT_SKIP (2025-07-11 15:30:27 -0600)

are available in the Git repository at:

  https://github.com/ammarfaizi2/liburing.git tags/gh-bot-musl-build-2025-07-14

for you to fetch changes up to 427dde341dc8c90b6288107325c7fd92353bb0ba:

  github: ci: Add alpine musl build (2025-07-14 11:08:21 +0700)

----------------------------------------------------------------
Pull musl build-test for GitHub Action Bot from Ammar Faizi:

  - Fix test/timestamp.c build error on musl libc env.

  - Add musl build-test for GitHub Action Bot.

----------------------------------------------------------------
Ammar Faizi (2):
      t/timestamp: Remove `#include <error.h>` and move `#include <time.h>` to the top
      github: ci: Add alpine musl build

 .github/workflows/ci.yml | 43 ++++++++++++++++++++++++++++++++++++++++
 test/timestamp.c         | 18 ++++++++---------
 2 files changed, 51 insertions(+), 10 deletions(-)

-- 
Ammar Faizi