Build libinputflinger for host

We don't have a usecase for it today, but the main motivation here is to
unify the target and host build parameters.

Also, this exposed an issue where ::write wasn't wrapped.

The host build produced an error:
frameworks/native/services/inputflinger/InputManager.cpp:189:5: error: ignoring return value of function declared with 'warn_unused_result' attribute [-Werror,-Wunused-result]
    ::write(fd, dump.c_str(), dump.size());

Bug: 271455682
Test: m libinputflinger
Change-Id: If1abc85b230f8e928422dab4c6bb33834b6393ee
diff --git a/services/inputflinger/Android.bp b/services/inputflinger/Android.bp
index 8f62629..f4aab3b 100644
--- a/services/inputflinger/Android.bp
+++ b/services/inputflinger/Android.bp
@@ -118,6 +118,7 @@
 
 cc_library_shared {
     name: "libinputflinger",
+    host_supported: true,
     defaults: [
         "inputflinger_defaults",
         "libinputflinger_defaults",
diff --git a/services/inputflinger/InputManager.cpp b/services/inputflinger/InputManager.cpp
index 1a9f47d..09c88ba 100644
--- a/services/inputflinger/InputManager.cpp
+++ b/services/inputflinger/InputManager.cpp
@@ -186,7 +186,7 @@
 
     dump += " InputFlinger dump\n";
 
-    ::write(fd, dump.c_str(), dump.size());
+    TEMP_FAILURE_RETRY(::write(fd, dump.c_str(), dump.size()));
     return NO_ERROR;
 }