[libc][i386] define MINSIGSTKSZ & SIGSTKSZ (llvm#114249)

Link: llvm#93709

Author: nickdesaulniers

libc/include/llvm-libc-macros/linux/signal-macros.h

@@ -76,15 +76,12 @@
 #define SS_ONSTACK 0x1
 #define SS_DISABLE 0x2
 
-#ifdef __x86_64__
+#if defined(__x86_64__) || defined(__i386__) || defined(__riscv)
 #define MINSIGSTKSZ 2048
 #define SIGSTKSZ 8192
 #elif defined(__aarch64__)
 #define MINSIGSTKSZ 5120
 #define SIGSTKSZ 16384
-#elif defined(__riscv)
-#define MINSIGSTKSZ 2048
-#define SIGSTKSZ 8192
 #else
 #error "Signal stack sizes not defined for your platform."
 #endif