[gdb/testsuite] Require syscall time in gdb.reverse/time-reverse.exp

On aarch64-linux, I run into:
...
Running gdb.reverse/time-reverse.exp ...
gdb compile failed, gdb.reverse/time-reverse.c: In function 'main':
gdb.reverse/time-reverse.c:39:12: error: 'SYS_time' undeclared \
  (first use in this function); did you mean 'SYS_times'?
   syscall (SYS_time, &time_global);
            ^~~~~~~~
            SYS_times
gdb.reverse/time-reverse.c:39:12: note: each undeclared identifier is \
  reported only once for each function it appears in
UNTESTED: gdb.reverse/time-reverse.exp: failed to prepare
...

Fix this by adding a new proc have_syscall, and requiring syscall time, such
that we have instead:
...
UNSUPPORTED: gdb.reverse/time-reverse.exp: require failed: \
  expr [have_syscall time]
...

Tested on x86_64-linux and aarch64-linux.

2 files changed, 13 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.reverse/time-reverse.exp b/gdb/testsuite/gdb.reverse/time-reverse.exp
index 07d55b3..befda65 100644
--- a/gdb/testsuite/gdb.reverse/time-reverse.exp
+++ b/gdb/testsuite/gdb.reverse/time-reverse.exp
@@ -23,6 +23,8 @@ require supports_reverse
 
 standard_testfile
 
+require {expr [have_syscall time]}
+
 if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
     return -1
 }
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index e48228e..12839a5 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -9397,5 +9397,16 @@ gdb_caching_proc linux_kernel_version {
     return [list $v1 $v2 $v3]
 }
 
+# Return 1 if syscall NAME is supported.
+
+proc have_syscall { name } {
+    set src \
+	[list \
+	     "#include <sys/syscall.h>" \
+	     "int var = SYS_$name;"]
+    set src [join $src "\n"]
+    return [gdb_can_simple_compile have_syscall_$name $src object]
+}
+
 # Always load compatibility stuff.
 load_lib future.exp