Continue using the legacy NDK android/log.h.

system/core/android/log.h needs some work before it can be included in
the NDK. It defines a *lot* of macros that previously were usable
names in NDK sources that used android/log.h. As an example, the
following file defines LOG_TAG as a variable, but the variable name
gets macro replaced if we use the current android/log.h.
https://android.googlesource.com/platform/external/deqp/+/4adc1515f867b26c19c2f7498e9de93a230a234d/framework/platform/android/tcuTestLogParserJNI.cpp#41

For now, we keep a copy of the old NDK android/log.h in
legacy-ndk-includes.

Test: make checkbuild
Bug: http://b/30465923
Change-Id: I8ce942d1ee2f8f0d4c27130802c03992a1b85ec4
diff --git a/liblog/Android.bp b/liblog/Android.bp
index c59dde9..bbaced5 100644
--- a/liblog/Android.bp
+++ b/liblog/Android.bp
@@ -91,6 +91,21 @@
     compile_multilib: "both",
 }
 
+// system/core/android/log.h needs some work before it can be included in the
+// NDK. It defines a *lot* of macros that previously were usable names in NDK
+// sources that used android/log.h. As an example, the following file defines
+// LOG_TAG as a variable, but the variable name gets macro replaced if we use
+// the current android/log.h.
+// https://android.googlesource.com/platform/external/deqp/+/4adc1515f867b26c19c2f7498e9de93a230a234d/framework/platform/android/tcuTestLogParserJNI.cpp#41
+//
+// For now, we keep a copy of the old NDK android/log.h in legacy-ndk-includes.
+ndk_headers {
+    name: "liblog_headers",
+    from: "legacy-ndk-includes",
+    to: "android",
+    srcs: ["legacy-ndk-includes/log.h"],
+}
+
 ndk_library {
     name: "liblog.ndk",
     symbol_file: "liblog.map.txt",