Put BacktraceOffline code into a separate library.

BacktraceOffline is the only code that uses libLLVM. Create
a new shared library, backtrace_offline.so, that references this
so that including libbacktrace.so doesn't wind up pulling in libLLVM.

Change-Id: I90c502d833f6c464c3810dffde52a0c6da241cce

libbacktrace/Android.mk

@@ -48,7 +48,6 @@ libbacktrace_src_files := \
 	Backtrace.cpp \
 	BacktraceCurrent.cpp \
 	BacktraceMap.cpp \
-	BacktraceOffline.cpp \
 	BacktracePtrace.cpp \
 	thread_utils.c \
 	ThreadEntry.cpp \
@@ -61,25 +60,6 @@ libbacktrace_shared_libraries := \
 	liblog \
 	libunwind \
 
-# Use shared llvm library on device to save space.
-libbacktrace_shared_libraries_target := \
-	libLLVM \
-
-# Use static llvm libraries on host to remove dependency on 32-bit llvm shared library
-# which is not included in the prebuilt.
-libbacktrace_static_libraries_host := \
-	libcutils \
-	libLLVMObject \
-	libLLVMBitReader \
-	libLLVMMC \
-	libLLVMMCParser \
-	libLLVMCore \
-	libLLVMSupport \
-
-libbacktrace_ldlibs_host := \
-	-lpthread \
-	-lrt \
-
 module := libbacktrace
 module_tag := optional
 build_type := target
@@ -97,6 +77,40 @@ build_target := STATIC_LIBRARY
 include $(LOCAL_PATH)/Android.build.mk
 libbacktrace_static_libraries :=
 
+#-------------------------------------------------------------------------
+# The libbacktrace_offline shared library.
+#-------------------------------------------------------------------------
+libbacktrace_offline_src_files := \
+	BacktraceOffline.cpp \
+
+libbacktrace_offline_shared_libraries := \
+	libbacktrace \
+	liblog \
+	libunwind \
+
+# Use shared llvm library on device to save space.
+libbacktrace_offline_shared_libraries_target := \
+	libLLVM \
+
+# Use static llvm libraries on host to remove dependency on 32-bit llvm shared library
+# which is not included in the prebuilt.
+libbacktrace_offline_static_libraries_host := \
+	libLLVMObject \
+	libLLVMBitReader \
+	libLLVMMC \
+	libLLVMMCParser \
+	libLLVMCore \
+	libLLVMSupport \
+
+module := libbacktrace_offline
+module_tag := optional
+build_type := target
+build_target := SHARED_LIBRARY
+include $(LOCAL_PATH)/Android.build.mk
+build_type := host
+libbacktrace_multilib := both
+include $(LOCAL_PATH)/Android.build.mk
+
 #-------------------------------------------------------------------------
 # The libbacktrace_test library needed by backtrace_test.
 #-------------------------------------------------------------------------
@@ -141,6 +155,7 @@ backtrace_test_ldlibs_host := \
 backtrace_test_shared_libraries := \
 	libbacktrace_test \
 	libbacktrace \
+	libbacktrace_offline \
 	libbase \
 	libcutils \
 	libunwind \

libbacktrace/Backtrace.cpp

@@ -28,7 +28,6 @@
 #include <backtrace/BacktraceMap.h>
 
 #include "BacktraceLog.h"
-#include "BacktraceOffline.h"
 #include "thread_utils.h"
 #include "UnwindCurrent.h"
 #include "UnwindPtrace.h"
@@ -149,8 +148,3 @@ Backtrace* Backtrace::Create(pid_t pid, pid_t tid, BacktraceMap* map) {
     return new UnwindPtrace(pid, tid, map);
   }
 }
-
-Backtrace* Backtrace::CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
-                                    const backtrace_stackinfo_t& stack, bool cache_file) {
-  return new BacktraceOffline(pid, tid, map, stack, cache_file);
-}

libbacktrace/BacktraceOffline.cpp

@@ -659,3 +659,8 @@ static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename) {
   }
   return nullptr;
 }
+
+Backtrace* Backtrace::CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
+                                    const backtrace_stackinfo_t& stack, bool cache_file) {
+  return new BacktraceOffline(pid, tid, map, stack, cache_file);
+}