fix signal.h breakage from moving stack_t to arch-specific bits

in the previous changes, I missed the fact that both the prototype of
the sigaltstack function and the definition of ucontext_t depend on
stack_t.

arch/arm/bits/signal.h

@@ -18,6 +18,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -27,12 +33,6 @@ typedef struct __ucontext {
 	unsigned long long uc_regspace[64];
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  2
 #define SA_SIGINFO    4

arch/i386/bits/signal.h

@@ -53,6 +53,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -62,12 +68,6 @@ typedef struct __ucontext {
 	unsigned long __fpregs_mem[28];
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  2
 #define SA_SIGINFO    4

arch/microblaze/bits/signal.h

@@ -21,6 +21,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -29,12 +35,6 @@ typedef struct __ucontext {
 	sigset_t uc_sigmask;
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  2
 #define SA_SIGINFO    4

arch/mips/bits/signal.h

@@ -38,6 +38,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	size_t ss_size;
+	int ss_flags;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -46,12 +52,6 @@ typedef struct __ucontext {
 	sigset_t uc_sigmask;
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	size_t ss_size;
-	int ss_flags;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  0x10000
 #define SA_SIGINFO    8

arch/powerpc/bits/signal.h

@@ -49,6 +49,12 @@ typedef struct {
 
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -60,12 +66,6 @@ typedef struct __ucontext {
 	mcontext_t uc_mcontext;
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1U
 #define SA_NOCLDWAIT  2U
 #define SA_SIGINFO    4U

arch/sh/bits/signal.h

@@ -19,6 +19,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -27,12 +33,6 @@ typedef struct __ucontext {
 	sigset_t uc_sigmask;
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  2
 #define SA_SIGINFO    4

arch/x32/bits/signal.h

@@ -60,6 +60,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -69,12 +75,6 @@ typedef struct __ucontext {
 	unsigned long long __fpregs_mem[64];
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  2
 #define SA_SIGINFO    4

arch/x86_64/bits/signal.h

@@ -60,6 +60,12 @@ typedef struct {
 } mcontext_t;
 #endif
 
+struct sigaltstack {
+	void *ss_sp;
+	int ss_flags;
+	size_t ss_size;
+};
+
 typedef struct __ucontext {
 	unsigned long uc_flags;
 	struct __ucontext *uc_link;
@@ -69,12 +75,6 @@ typedef struct __ucontext {
 	unsigned long __fpregs_mem[64];
 } ucontext_t;
 
-typedef struct sigaltstack {
-	void *ss_sp;
-	int ss_flags;
-	size_t ss_size;
-} stack_t;
-
 #define SA_NOCLDSTOP  1
 #define SA_NOCLDWAIT  2
 #define SA_SIGINFO    4

include/signal.h

@@ -77,6 +77,8 @@ extern "C" {
 #define CLD_STOPPED 5
 #define CLD_CONTINUED 6
 
+typedef struct sigaltstack stack_t;
+
 union sigval {
 	int sival_int;
 	void *sival_ptr;