adbd: improve coverage by compiling less code.

Test: ./coverage/gen_coverage.sh && ./coverage/report.sh
Change-Id: I26f823e2587435b7ec2c6ca05955adef5cfc23a0
diff --git a/adb/Android.bp b/adb/Android.bp
index 19e921f..8779c0a 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -165,7 +165,6 @@
     "adb_unique_fd.cpp",
     "adb_utils.cpp",
     "fdevent/fdevent.cpp",
-    "fdevent/fdevent_poll.cpp",
     "services.cpp",
     "sockets.cpp",
     "socket_spec.cpp",
@@ -176,6 +175,17 @@
     "types.cpp",
 ]
 
+libadb_darwin_srcs = [
+    "fdevent/fdevent_poll.cpp",
+]
+
+libadb_windows_srcs = [
+    "fdevent/fdevent_poll.cpp",
+    "sysdeps_win32.cpp",
+    "sysdeps/win32/errno.cpp",
+    "sysdeps/win32/stat.cpp",
+]
+
 libadb_posix_srcs = [
     "sysdeps_unix.cpp",
     "sysdeps/posix/network.cpp",
@@ -219,7 +229,7 @@
             srcs: ["client/usb_linux.cpp"] + libadb_linux_srcs,
         },
         darwin: {
-            srcs: ["client/usb_osx.cpp"],
+            srcs: ["client/usb_osx.cpp"] + libadb_darwin_srcs,
         },
         not_windows: {
             srcs: libadb_posix_srcs,
@@ -228,10 +238,7 @@
             enabled: true,
             srcs: [
                 "client/usb_windows.cpp",
-                "sysdeps_win32.cpp",
-                "sysdeps/win32/errno.cpp",
-                "sysdeps/win32/stat.cpp",
-            ],
+            ] + libadb_windows_srcs,
             shared_libs: ["AdbWinApi"],
         },
     },