test: add test for getsid_test.cpp to check for failing getsid syscall

This commit also do cleanup on libc/src/unistd/linux/CMakeLists.txt to remove
unnecessary fnctl_macros and unistd from add_entrypoint_object for getsid

Signed-off-by: ZakyHermawan <[email protected]>

Author: ZakyHermawan

libc/src/unistd/linux/CMakeLists.txt

@@ -243,8 +243,6 @@ add_entrypoint_object(
     ../getsid.h
   DEPENDS
     libc.hdr.types.pid_t
-    libc.hdr.fcntl_macros
-    libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
     libc.src.errno.errno

libc/test/src/unistd/getsid_test.cpp

@@ -14,4 +14,8 @@ TEST(LlvmLibcGetPidTest, GetCurrSID) {
   pid_t sid = LIBC_NAMESPACE::getsid(0);
   ASSERT_NE(sid, -1);
   ASSERT_ERRNO_SUCCESS();
+
+  pid_t nonexist_sid = LIBC_NAMESPACE::getsid(999999);
+  ASSERT_EQ(nonexist_sid, -1);
+  ASSERT_ERRNO_FAILURE();
 }