test: rename file with stub functions

icmp6-util-linux.c sounds like a specialized implementation of the functions in
icmp6-util.c. But it's just a set of stub versions used in tests. Rename the
file to make this more obvious.

src/libsystemd-network/fuzz-ndisc-rs.c

@@ -11,7 +11,7 @@
 #include "fd-util.h"
 #include "fuzz.h"
 #include "icmp6-packet.h"
-#include "icmp6-util-unix.h"
+#include "icmp6-test-util.h"
 #include "ndisc-internal.h"
 #include "ndisc-option.h"
 #include "socket-util.h"

src/libsystemd-network/icmp6-test-util.c

@@ -5,7 +5,7 @@
 #include <unistd.h>
 
 #include "fd-util.h"
-#include "icmp6-util-unix.h"
+#include "icmp6-test-util.h"
 
 int test_fd[2] = EBADF_PAIR;
 

src/libsystemd-network/meson.build

@@ -91,13 +91,13 @@ executables += [
         network_test_template + {
                 'sources' : files(
                         'test-ndisc-ra.c',
-                        'icmp6-util-unix.c',
+                        'icmp6-test-util.c',
                 ),
         },
         network_test_template + {
                 'sources' : files(
                         'test-ndisc-rs.c',
-                        'icmp6-util-unix.c',
+                        'icmp6-test-util.c',
                 ),
         },
         network_test_template + {
@@ -125,7 +125,7 @@ executables += [
         network_fuzz_template + {
                 'sources' : files(
                         'fuzz-ndisc-rs.c',
-                        'icmp6-util-unix.c',
+                        'icmp6-test-util.c',
                 ),
         },
 ]

src/libsystemd-network/test-ndisc-ra.c

@@ -11,7 +11,7 @@
 
 #include "alloc-util.h"
 #include "hexdecoct.h"
-#include "icmp6-util-unix.h"
+#include "icmp6-test-util.h"
 #include "socket-util.h"
 #include "strv.h"
 #include "tests.h"

src/libsystemd-network/test-ndisc-rs.c

@@ -13,7 +13,7 @@
 #include "fd-util.h"
 #include "hexdecoct.h"
 #include "icmp6-packet.h"
-#include "icmp6-util-unix.h"
+#include "icmp6-test-util.h"
 #include "socket-util.h"
 #include "strv.h"
 #include "ndisc-internal.h"