Merge "libc.map.txt: remove the two riscv64 special cases." into main

Author: enh-google

libc/libc.map.txt

@@ -956,7 +956,7 @@ LIBC {
     sigaction;
     sigaddset;
     sigaltstack;
-    sigblock; # arm x86 arm64 x86_64
+    sigblock;
     sigdelset;
     sigemptyset;
     sigfillset;
@@ -969,7 +969,7 @@ LIBC {
     sigprocmask;
     sigqueue; # introduced=23
     sigsetjmp;
-    sigsetmask; # arm x86 arm64 x86_64
+    sigsetmask;
     sigsuspend;
     sigtimedwait; # introduced=23
     sigwait;