aarch64: copy the sigcontext structure from the kernel headers

Its declaration was changed in glibc headers and we don't want
to handle two version of itю

In file included from compel/include/uapi/compel/infect.h:6:0,
                 from compel/include/uapi/compel/compel.h:12,
                 from compel/include/log.h:4,
                 from compel/arch/aarch64/src/lib/infect.c:8:
compel/arch/aarch64/src/lib/infect.c: In function 'sigreturn_prep_regs_plain':
compel/include/uapi/compel/asm/sigframe.h:47:99: error: 'mcontext_t {aka struct <anonymous>}' has no member named '__reserved'; did you mean '__glibc_reserved1'?
 #define RT_SIGFRAME_AUX_CONTEXT(rt_sigframe) ((struct aux_context*)&(rt_sigframe)->uc.uc_mcontext.__reserved)
                                                                                                   ^
compel/include/uapi/compel/asm/sigframe.h:48:41: note: in expansion of macro 'RT_SIGFRAME_AUX_CONTEXT'
 #define RT_SIGFRAME_FPU(rt_sigframe)  (&RT_SIGFRAME_AUX_CONTEXT(rt_sigframe)->fpsimd)
                                         ^~~~~~~~~~~~~~~~~~~~~~~
compel/arch/aarch64/src/lib/infect.c:34:34: note: in expansion of macro 'RT_SIGFRAME_FPU'
  struct fpsimd_context *fpsimd = RT_SIGFRAME_FPU(sigframe);
                                  ^~~~~~~~~~~~~~~
make[1]: *** [/builddir/build/BUILD/criu-3.5/scripts/nmk/scripts/build.mk:209: compel/arch/aarch64/src/lib/infect.o] Error 1
make: *** [Makefile.compel:36: compel/libcompel.a] Error 2
error: Bad exit status from /var/tmp/rpm-tmp.IExY9K (%build)

This seems to be related to the following glibc changes:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=4fa9b3bfe6759c82beb4b043a54a3598ca467289Reported-by: Adrian Reber <adrian@lisas.de>
Tested-by: Adrian Reber <adrian@lisas.de>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

compel/arch/aarch64/src/lib/include/uapi/asm/sigframe.h

@@ -41,10 +41,23 @@ struct rt_sigframe {
 			: "r"(new_sp)						\
 			: "sp", "x8", "memory")
 
+/* cr_sigcontext is copied from arch/arm64/include/uapi/asm/sigcontext.h */
+struct cr_sigcontext {
+        __u64 fault_address;
+        /* AArch64 registers */
+        __u64 regs[31];
+        __u64 sp;
+        __u64 pc;
+        __u64 pstate;
+        /* 4K reserved for FP/SIMD state and future expansion */
+        __u8 __reserved[4096] __attribute__((__aligned__(16)));
+};
+
 #define RT_SIGFRAME_UC(rt_sigframe)		(&rt_sigframe->uc)
 #define RT_SIGFRAME_REGIP(rt_sigframe)		((long unsigned int)(rt_sigframe)->uc.uc_mcontext.pc)
 #define RT_SIGFRAME_HAS_FPU(rt_sigframe)	(1)
-#define RT_SIGFRAME_AUX_CONTEXT(rt_sigframe)	((struct aux_context*)&(rt_sigframe)->uc.uc_mcontext.__reserved)
+#define RT_SIGFRAME_SIGCONTEXT(rt_sigframe)	((struct cr_sigcontext *)&(rt_sigframe)->uc.uc_mcontext)
+#define RT_SIGFRAME_AUX_CONTEXT(rt_sigframe)	((struct aux_context*)&(RT_SIGFRAME_SIGCONTEXT(rt_sigframe)->__reserved))
 #define RT_SIGFRAME_FPU(rt_sigframe)		(&RT_SIGFRAME_AUX_CONTEXT(rt_sigframe)->fpsimd)
 #define RT_SIGFRAME_OFFSET(rt_sigframe)		0