Add a "fork" of musl as //fusl.

fusl/arch/arm/bits/signal.h

+#if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \
+ || defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+
+#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#define MINSIGSTKSZ 2048
+#define SIGSTKSZ 8192
+#endif
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+typedef int greg_t, gregset_t[18];
+typedef struct sigcontext
+{
+        unsigned long trap_no, error_code, oldmask;
+        unsigned long arm_r0, arm_r1, arm_r2, arm_r3;
+        unsigned long arm_r4, arm_r5, arm_r6, arm_r7;
+        unsigned long arm_r8, arm_r9, arm_r10, arm_fp;
+        unsigned long arm_ip, arm_sp, arm_lr, arm_pc;
+        unsigned long arm_cpsr, fault_address;
+} mcontext_t;
+#else
+typedef struct {
+        unsigned long __regs[21];
+} 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;
+        stack_t uc_stack;
+        mcontext_t uc_mcontext;
+        sigset_t uc_sigmask;
+        unsigned long long uc_regspace[64];
+} ucontext_t;
+
+#define SA_NOCLDSTOP  1
+#define SA_NOCLDWAIT  2
+#define SA_SIGINFO    4
+#define SA_ONSTACK    0x08000000
+#define SA_RESTART    0x10000000
+#define SA_NODEFER    0x40000000
+#define SA_RESETHAND  0x80000000
+#define SA_RESTORER   0x04000000
+
+#endif
+
+#define SIGHUP    1
+#define SIGINT    2
+#define SIGQUIT   3
+#define SIGILL    4
+#define SIGTRAP   5
+#define SIGABRT   6
+#define SIGIOT    SIGABRT
+#define SIGBUS    7
+#define SIGFPE    8
+#define SIGKILL   9
+#define SIGUSR1   10
+#define SIGSEGV   11
+#define SIGUSR2   12
+#define SIGPIPE   13
+#define SIGALRM   14
+#define SIGTERM   15
+#define SIGSTKFLT 16
+#define SIGCHLD   17
+#define SIGCONT   18
+#define SIGSTOP   19
+#define SIGTSTP   20
+#define SIGTTIN   21
+#define SIGTTOU   22
+#define SIGURG    23
+#define SIGXCPU   24
+#define SIGXFSZ   25
+#define SIGVTALRM 26
+#define SIGPROF   27
+#define SIGWINCH  28
+#define SIGIO     29
+#define SIGPOLL   29
+#define SIGPWR    30
+#define SIGSYS    31
+#define SIGUNUSED SIGSYS
+
+#define _NSIG 65