meson: remove obsolete check for BPF_PROG_QUERY

The BPF_PROG_QUERY constant was introduced to Linux in

  commit defd9c476fa6b01b4eb5450452bfd202138decb7
  Author: Alexei Starovoitov <ast@kernel.org>
  Date:   Mon Oct 2 22:50:26 2017 -0700

    libbpf: sync bpf.h

This is old enough that all our supported platforms can be assumed
to have this feature.

Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

meson.build

@@ -647,7 +647,6 @@ symbols = [
 if host_machine.system() == 'linux'
   symbols += [
     # Check if we have new enough kernel to support BPF devices for cgroups v2
-    [ 'linux/bpf.h', 'BPF_PROG_QUERY' ],
     [ 'linux/bpf.h', 'BPF_CGROUP_DEVICE' ],
   ]
 endif

src/util/virbpf.c

@@ -24,7 +24,7 @@ VIR_LOG_INIT("util.bpf");
 
 #define VIR_FROM_THIS VIR_FROM_BPF
 
-#if WITH_SYS_SYSCALL_H && WITH_DECL_BPF_PROG_QUERY
+#ifdef __linux__
 # include <sys/syscall.h>
 # include <unistd.h>
 
@@ -292,7 +292,7 @@ virBPFDeleteElem(int mapfd,
 }
 
 
-#else /* !WITH_SYS_SYSCALL_H || !WITH_DECL_BPF_PROG_QUERY */
+#else /* ! __linux__ */
 
 
 int
@@ -420,4 +420,4 @@ virBPFDeleteElem(int mapfd G_GNUC_UNUSED,
     errno = ENOSYS;
     return -1;
 }
-#endif /* !WITH_SYS_SYSCALL_H || !WITH_DECL_BPF_PROG_QUERY */
+#endif /* !__linux__ */

src/util/virbpf.h

@@ -18,7 +18,7 @@
 
 #pragma once
 
-#if WITH_DECL_BPF_PROG_QUERY
+#ifdef __linux__
 
 # include <linux/bpf.h>
 
@@ -171,7 +171,7 @@
      .imm = 0, \
      })
 
-#else /* WITH_DECL_BPF_PROG_QUERY */
+#else /* ! __linux__ */
 
 struct bpf_prog_info;
 struct bpf_map_info;
@@ -191,7 +191,7 @@ struct bpf_insn;
 # define VIR_BPF_CALL_INSN(func)
 # define VIR_BPF_EXIT_INSN()
 
-#endif /* WITH_DECL_BPF_PROG_QUERY */
+#endif /* ! __linux__ */
 
 int
 virBPFCreateMap(unsigned int mapType,