[libc] Add ppoll stub to match existing pselect stub. NFC (#26084)

This is mostly just for consistency and completeness.

Author: sbc100

system/lib/libc/emscripten_syscall_stubs.c

@@ -264,6 +264,7 @@ UNIMPLEMENTED(acct, (intptr_t filename))
 UNIMPLEMENTED(mincore, (intptr_t addr, size_t length, intptr_t vec))
 UNIMPLEMENTED(pipe2, (intptr_t fds, int flags))
 UNIMPLEMENTED(pselect6, (int nfds, intptr_t readfds, intptr_t writefds, intptr_t exceptfds, intptr_t timeout, intptr_t sigmaks))
+UNIMPLEMENTED(ppoll, (intptr_t fds, int nfds, intptr_t timeout, intptr_t sigmask, int size))
 UNIMPLEMENTED(recvmmsg, (int sockfd, intptr_t msgvec, size_t vlen, int flags, ...))
 UNIMPLEMENTED(sendmmsg, (int sockfd, intptr_t msgvec, size_t vlen, int flags, ...))
 UNIMPLEMENTED(shutdown, (int sockfd, int how, int dummy, int dummy2, int dummy3, int dummy4))

system/lib/libc/musl/arch/emscripten/bits/syscall.h

@@ -67,6 +67,7 @@
 #define SYS_fchmodat2		__syscall_fchmodat2
 #define SYS_faccessat		__syscall_faccessat
 #define SYS_pselect6		__syscall_pselect6
+#define SYS_ppoll		__syscall_ppoll
 #define SYS_utimensat		__syscall_utimensat
 #define SYS_fallocate		__syscall_fallocate
 #define SYS_dup3		__syscall_dup3

system/lib/libc/musl/arch/emscripten/syscall_arch.h

@@ -91,6 +91,7 @@ int __syscall_readlinkat(int dirfd, intptr_t path, intptr_t buf, size_t bufsize)
 int __syscall_fchmodat2(int dirfd, intptr_t path, int mode, int flags);
 int __syscall_faccessat(int dirfd, intptr_t path, int amode, int flags);
 int __syscall_pselect6(int nfds, intptr_t readfds, intptr_t writefds, intptr_t exceptfds, intptr_t timeout, intptr_t sigmask);
+int __syscall_ppoll(intptr_t fds, int nfds, intptr_t timeout, intptr_t sigmask, int size);
 int __syscall_utimensat(int dirfd, intptr_t path, intptr_t times, int flags);
 int __syscall_fallocate(int fd, int mode, off_t offset, off_t len);
 int __syscall_dup3(int fd, int suggestfd, int flags);

test/codesize/test_codesize_hello_dylink_all.json

@@ -1,7 +1,7 @@
 {
   "a.out.js": 244848,
-  "a.out.nodebug.wasm": 577782,
-  "total": 822630,
+  "a.out.nodebug.wasm": 577879,
+  "total": 822727,
   "sent": [
     "IMG_Init",
     "IMG_Load",
@@ -1892,6 +1892,7 @@
     "__syscall_pause",
     "__syscall_pipe2",
     "__syscall_poll",
+    "__syscall_ppoll",
     "__syscall_prlimit64",
     "__syscall_pselect6",
     "__syscall_recvmmsg",
@@ -2829,6 +2830,7 @@
     "pow10l",
     "powf",
     "powl",
+    "ppoll",
     "pread",
     "preadv",
     "printf",
@@ -3756,9 +3758,9 @@
     "$__syscall_pause",
     "$__syscall_pipe2",
     "$__syscall_poll",
+    "$__syscall_ppoll",
     "$__syscall_prlimit64",
     "$__syscall_pselect6",
-    "$__syscall_recvmmsg",
     "$__syscall_setdomainname",
     "$__syscall_setpgid",
     "$__syscall_setpriority",
@@ -4597,6 +4599,7 @@
     "$pow",
     "$powf",
     "$powl",
+    "$ppoll",
     "$pread",
     "$preadv",
     "$printf",

tools/system_libs.py

@@ -1153,7 +1153,6 @@ def get_files(self):
         'memcpy.c', 'memset.c', 'memmove.c', 'getaddrinfo.c', 'getnameinfo.c',
         'res_query.c', 'res_querydomain.c',
         'proto.c',
-        'ppoll.c',
         'syscall.c', 'popen.c', 'pclose.c',
         'getgrouplist.c', 'initgroups.c', 'wordexp.c', 'timer_create.c',
         'getauxval.c',