feat: add SYS_GETCAPS syscall to retrieve process capabilities

programs/include/montauk/syscall.h

@@ -127,6 +127,10 @@ namespace montauk {
                              (uint64_t)args, (uint64_t)user,
                              (uint64_t)&capabilities);
     }
+    // The calling process's own capability masks. Returns 0 on success.
+    inline int getcaps(montauk::abi::SpawnCapabilities* out) {
+        return (int)syscall1(montauk::abi::SYS_GETCAPS, (uint64_t)out);
+    }
     inline int chdir(const char* path) {
         return (int)syscall1(montauk::abi::SYS_CHDIR, (uint64_t)path);
     }