Allow sched_getparam in the process sandbox.

glibc's pthread_getschedparam() issues both sched_getscheduler and
sched_getparam; the allowlist only covered the former, so the Compositor
process dies with "Sandbox violation: disallowed syscall (143)" on
kernels/userlands that exercise this path (observed on linux-cachyos).

--- a/Libraries/LibSandbox/Seccomp.cpp
+++ b/Libraries/LibSandbox/Seccomp.cpp
@@ -1226,6 +1226,10 @@
     append(BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_sched_getscheduler, 0, 1));
     append(SECCOMP_ALLOW);
 #endif
+#ifdef __NR_sched_getparam
+    append(BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_sched_getparam, 0, 1));
+    append(SECCOMP_ALLOW);
+#endif
 #ifdef __NR_sched_get_priority_max
     append(BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_sched_get_priority_max, 0, 1));
     append(SECCOMP_ALLOW);