Implement -e kvm= option on all architectures

Make -e kvm= interface available on all architectures by adding a stub
on those architectures that do not have <linux/kvm.h>.

* filter_qualify.c (qualify_kvm): Define unconditionally.
(qual_options): Define qualify_kvm entry unconditionally.
* strace.c (usage): Mention kvm argument of -e option unconditionally.

filter_qualify.c

@@ -405,20 +405,24 @@ qualify_inject(const char *const str)
 	qualify_inject_common(str, false, "inject argument");
 }
 
-#ifdef HAVE_LINUX_KVM_H
 static void
 qualify_kvm(const char *const str)
 {
 	if (strcmp(str, "vcpu") == 0) {
+#ifdef HAVE_LINUX_KVM_H
 		if (os_release >= KERNEL_VERSION(4, 16, 0))
 			kvm_run_structure_decoder_init();
 		else
-			error_msg("-e kvm=vcpu option needs Linux 4.16.0 or higher");
+			error_msg("-e kvm=vcpu option needs"
+				  " Linux 4.16.0 or higher");
+#else
+		error_msg("-e kvm=vcpu option is not implemented"
+			  " for this architecture");
+#endif
 	} else {
 		error_msg_and_die("invalid -e kvm= argument: '%s'", str);
 	}
 }
-#endif
 
 static const struct qual_options {
 	const char *name;
@@ -443,9 +447,7 @@ static const struct qual_options {
 	{ "w",		qualify_write	},
 	{ "fault",	qualify_fault	},
 	{ "inject",	qualify_inject	},
-#ifdef HAVE_LINUX_KVM_H
 	{ "kvm",	qualify_kvm	},
-#endif
 };
 
 void

strace.c

@@ -278,10 +278,7 @@ Statistics:\n\
 \n\
 Filtering:\n\
   -e expr        a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\
-     options:    trace, abbrev, verbose, raw, signal, read, write, fault, inject"
-#ifdef HAVE_LINUX_KVM_H
-		", kvm"
-#endif
+     options:    trace, abbrev, verbose, raw, signal, read, write, fault, inject, kvm"
 "\n\
   -P path        trace accesses to path\n\
 \n\