NetBpfLoad: enable mainline on T+

Note:
   2 == BPFLOADER_S_VERSION
  19 == BPFLOADER_T_VERSION
  25 == BPFLOADER_OBJ_AT_VER_VERSION
  33 == BPFLOADER_IGNORED_ON_VERSION
  37 == BPFLOADER_U_VERSION [*]
  41 == BPFLOADER_V_VERSION [**]
and currently we have:
  42 == BPFLOADER_MAINLINE_VERSION
  43 == BPFLOADER_MAINLINE_T_VERSION
  44 == BPFLOADER_MAINLINE_U_VERSION
  45 == BPFLOADER_MAINLINE_V_VERSION

[*] udc-dev/udc-release are actually 38, as 37 was some earlier
    udc beta2 (2.1 ifirc), and beta3+ switched to 38

[**] 24Q{1,2}-release (ie. U QPR2+) are technically actually 41,
     but their platform bpfloader no longer even looks in /apex/com.android.tethering/etc/bpf/...
     so it doesn't really matter (although 24Q1's platform
     netbpfload still does, however that is obsoleted by
     this change)

Thus we need to (as minimum for NetBpfLoad):
  BPFLOADER_T_VERSION -> BPFLOADER_MAINLINE_T_VERSION
  BPFLOADER_IGNORED_ON_VERSION -> BPFLOADER_MAINLINE_U_VERSION
to cause these to load appropriately from mainline.

One would perhaps also expect (as minimum for NetBpfLoad):
  BPFLOADER_OBJ_AT_VERSION -> BPFLOADER_MAINLINE_U_VERSION
but (as maximum for platform bpfloader):
  BPFLOADER_OBJ_AT_VERSION -> BPFLOADER_MAINLINE_U_VERSION

However, since the goal is actually for those to load via mainline on T+,
(with the 'old' version of the .o's loading on S via platform bpfloader)
thus one actually needs (as minimum for NetBpfLoad):
  BPFLOADER_OBJ_AT_VERSION -> BPFLOADER_MAINLINE_T_VERSION
and (as maximum for platform bpfloader):
  BPFLOADER_OBJ_AT_VERSION -> BPFLOADER_T_VERSION

Test: TreeHugger
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I4b688692ffca0db7ead20cefd9e7e892ca92c70a
diff --git a/netbpfload/NetBpfLoad.cpp b/netbpfload/NetBpfLoad.cpp
index 196b687..9651a3b 100644
--- a/netbpfload/NetBpfLoad.cpp
+++ b/netbpfload/NetBpfLoad.cpp
@@ -261,9 +261,10 @@
         // Tethering apex shipped initrc file causes us to reach here
         // but we're not ready to correctly handle anything before U QPR2
         // in which the 'bpfloader' vs 'netbpfload' split happened
-        const char * args[] = { platformBpfLoader, NULL, };
-        execve(args[0], (char**)args, envp);
-        ALOGE("exec '%s' fail: %d[%s]", platformBpfLoader, errno, strerror(errno));
+    }
+
+    if (!isAtLeastT) {
+        ALOGE("Impossible - not reachable on Android <T.");
         return 1;
     }