Add libfieldnull static target.

Getting everything setup so jvmti agents can reach libbase can be
tricky. Get libfieldnull building statically.

Test: manual. Install agent
Change-Id: Id889636fd40bc39cca438bbb0d1e678dd0e1110f
diff --git a/tools/jvmti-agents/field-null-percent/Android.bp b/tools/jvmti-agents/field-null-percent/Android.bp
index 26bb1dc..52b4d89 100644
--- a/tools/jvmti-agents/field-null-percent/Android.bp
+++ b/tools/jvmti-agents/field-null-percent/Android.bp
@@ -16,18 +16,13 @@
 
 // Build variants {target,host} x {debug,ndebug} x {32,64}
 cc_defaults {
-    name: "fieldnull-defaults",
-    host_supported: true,
+    name: "fieldnull-base-defaults",
     srcs: ["fieldnull.cc"],
     defaults: ["art_defaults"],
 
     // Note that this tool needs to be built for both 32-bit and 64-bit since it requires
     // to be same ISA as what it is attached to.
     compile_multilib: "both",
-
-    shared_libs: [
-        "libbase",
-    ],
     header_libs: [
         "libopenjdkjvmti_headers",
     ],
@@ -42,6 +37,35 @@
     symlink_preferred_arch: true,
 }
 
+cc_defaults {
+    name: "fieldnull-defaults",
+    host_supported: true,
+    shared_libs: [
+        "libbase",
+    ],
+    defaults: ["fieldnull-base-defaults"],
+}
+
+cc_defaults {
+    name: "fieldnull-static-defaults",
+    host_supported: false,
+    defaults: ["fieldnull-base-defaults"],
+
+    shared_libs: [
+        "liblog",
+    ],
+    static_libs: [
+        "libbase_ndk",
+    ],
+    sdk_version: "current",
+    stl: "c++_static",
+}
+
+cc_library {
+    name: "libfieldnulls",
+    defaults: ["fieldnull-static-defaults"],
+}
+
 art_cc_library {
     name: "libfieldnull",
     defaults: ["fieldnull-defaults"],
diff --git a/tools/jvmti-agents/field-null-percent/README.md b/tools/jvmti-agents/field-null-percent/README.md
index d8bc65d..c07c163 100644
--- a/tools/jvmti-agents/field-null-percent/README.md
+++ b/tools/jvmti-agents/field-null-percent/README.md
@@ -7,7 +7,7 @@
 
 # Usage
 ### Build
->    `make libfieldnull`
+>    `make libfieldnull libfieldnulls`
 
 The libraries will be built for 32-bit, 64-bit, host and target. Below examples
 assume you want to use the 64-bit version.
@@ -26,9 +26,9 @@
 
 >    `adb shell setenforce 0`
 >
->    `adb push $ANDROID_PRODUCT_OUT/system/lib64/libfieldnull.so /data/local/tmp/`
+>    `adb push $ANDROID_PRODUCT_OUT/system/lib64/libfieldnulls.so /data/local/tmp/`
 >
->    `adb shell am start-activity --attach-agent '/data/local/tmp/libfieldnull.so=Ljava/lang/Class;.name:Ljava/lang/String;' some.debuggable.apps/.the.app.MainActivity`
+>    `adb shell am start-activity --attach-agent '/data/local/tmp/libfieldnulls.so=Ljava/lang/Class;.name:Ljava/lang/String;' some.debuggable.apps/.the.app.MainActivity`
 
 #### RI
 >    `java '-agentpath:libfieldnull.so=Lname/of/class;.nameOfField:Ltype/of/field;' -cp tmp/helloworld/classes helloworld`