[libc] Add faccessat entrypoints for aarch64 and riscv (#165869)

Add faccessat entrypoints for aarch64 and riscv linux. Entrypoints are
removed if faccessat2 syscall is not available.

Author: mleleszi

libc/config/linux/aarch64/entrypoints.txt

@@ -325,8 +325,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup2
     libc.src.unistd.dup3
     libc.src.unistd.execve
-    # Disabled while SYS_faccessat2 is unavailable on the buildbot.
-    # libc.src.unistd.faccessat
+    libc.src.unistd.faccessat
     libc.src.unistd.fchdir
     libc.src.unistd.fpathconf
     libc.src.unistd.fsync

libc/config/linux/aarch64/exclude.txt

@@ -0,0 +1,8 @@
+include(CheckSymbolExists)
+check_symbol_exists(SYS_faccessat2 "sys/syscall.h" HAVE_SYS_FACCESSAT2)
+if(NOT HAVE_SYS_FACCESSAT2)
+  message(VERBOSE "unistd.faccessat excluded from build, faccessat2 syscall is not available on the system")
+  list(APPEND TARGET_LLVMLIBC_REMOVED_ENTRYPOINTS
+    libc.src.unistd.faccessat
+  )
+endif()

libc/config/linux/riscv/entrypoints.txt

@@ -329,6 +329,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup2
     libc.src.unistd.dup3
     libc.src.unistd.execve
+    libc.src.unistd.faccessat
     libc.src.unistd.fchdir
     libc.src.unistd.fpathconf
     libc.src.unistd.fsync

libc/config/linux/riscv/exclude.txt

@@ -0,0 +1,8 @@
+include(CheckSymbolExists)
+check_symbol_exists(SYS_faccessat2 "sys/syscall.h" HAVE_SYS_FACCESSAT2)
+if(NOT HAVE_SYS_FACCESSAT2)
+  message(VERBOSE "unistd.faccessat excluded from build, faccessat2 syscall is not available on the system")
+  list(APPEND TARGET_LLVMLIBC_REMOVED_ENTRYPOINTS
+    libc.src.unistd.faccessat
+  )
+endif()

libc/config/linux/x86_64/exclude.txt

@@ -23,6 +23,7 @@ endif()
 include(CheckSymbolExists)
 check_symbol_exists(SYS_faccessat2 "sys/syscall.h" HAVE_SYS_FACCESSAT2)
 if(NOT HAVE_SYS_FACCESSAT2)
+  message(VERBOSE "unistd.faccessat excluded from build, faccessat2 syscall is not available on the system")
   list(APPEND TARGET_LLVMLIBC_REMOVED_ENTRYPOINTS
     libc.src.unistd.faccessat
   )