Add some syscalls of signal

[yukiiiteru]

No description provided.

[wangrunji0408]

I resolved the conflicts and did some refactors of the code (cbff620) at branch signal.

Please review the code. If no problem, you can reset your branch to 'signal' and force push.

[coveralls]

Pull Request Test Coverage Report for Build 210943041

• 21 of 141 (14.89%) changed or added relevant lines in 6 files are covered.
• 7 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.3%) to 46.354%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
linux-syscall/src/lib.rs	0	3	0.0%
linux-object/src/process.rs	8	14	57.14%
linux-object/src/signal/action.rs	8	31	25.81%
linux-object/src/signal/mod.rs	3	40	7.5%
linux-syscall/src/signal.rs	0	51	0.0%

Files with Coverage Reduction	New Missed Lines	%
../../../../../usr/share/rust/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/bitflags-1.2.1/src/lib.rs	2	41.67%
../../../../../usr/share/rust/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/spin-0.5.2/src/mutex.rs	2	55.0%
linux-syscall/src/lib.rs	3	44.59%

Totals
Change from base Build 210611853:	-0.3%
Covered Lines:	6553
Relevant Lines:	14137

---

💛 - Coveralls

[yukiiiteru]

Thanks, I've force pushed, please check.

[coveralls]

Pull Request Test Coverage Report for Build 210943041

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 21 of 141 (14.89%) changed or added relevant lines in 6 files are covered.
• 7 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.3%) to 46.354%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
linux-syscall/src/lib.rs	0	3	0.0%
linux-object/src/process.rs	8	14	57.14%
linux-object/src/signal/action.rs	8	31	25.81%
linux-object/src/signal/mod.rs	3	40	7.5%
linux-syscall/src/signal.rs	0	51	0.0%

Files with Coverage Reduction	New Missed Lines	%
../../../../../usr/share/rust/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/bitflags-1.2.1/src/lib.rs	2	41.67%
../../../../../usr/share/rust/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/spin-0.5.2/src/mutex.rs	2	55.0%
linux-syscall/src/lib.rs	3	44.59%

Totals
Change from base Build 210611853:	-0.3%
Covered Lines:	6553
Relevant Lines:	14137

---

💛 - Coveralls