libbpf_android: waitForProgsLoaded

Creating a function for this rather than having people copy/paste a loop
there.

It's very intentional that there is no timeout here. If bpfloader is
down, there is a serious problem, and we shouldn't let code move forward
in a state where it may not have been tested.

Bug: 140330870
Test: boot & use bpf/netd
Change-Id: I358d1fcf77ad5406e294dd57307bc411e2c8ad6a
diff --git a/libbpf_android/include/libbpf_android.h b/libbpf_android/include/libbpf_android.h
index cea707c..0a01c85 100644
--- a/libbpf_android/include/libbpf_android.h
+++ b/libbpf_android/include/libbpf_android.h
@@ -23,8 +23,13 @@
 
 namespace android {
 namespace bpf {
+
 // BPF loader implementation. Loads an eBPF ELF object
 int loadProg(const char* elfpath);
+
+// Wait for bpfloader to load BPF programs.
+void waitForProgsLoaded();
+
 }  // namespace bpf
 }  // namespace android