add some information about the Xposed binary and the phone into the log

For example:
D/Xposed  (19345): Starting Xposed binary version 30, compiled for SDK 17
D/Xposed  (19345): Phone GT-I9100 (samsung), Android version 4.2.1 (SDK 17)
D/Xposed  (19345): ROM: cm_i9100-userdebug 4.2.1 JOP40D eng..20130105.024510 test-keys
I/Xposed  (19345): -----------------
I/Xposed  (19345): Added Xposed (/data/xposed/XposedBridge.jar) to CLASSPATH.
I/Xposed  (19345): Found Xposed class 'de/robv/android/xposed/XposedBridge', now initializing

app_main.cpp

@@ -194,6 +194,7 @@ int main(int argc, const char* const argv[])
 
     runtime.mParentDir = parentDir;
 
+    xposedInfo();
     keepLoadingXposed = !isXposedDisabled() && !xposedShouldIgnoreCommand(className, argc, argv) && addXposedToClasspath(zygote);
 
     if (zygote) {

xposed.cpp

@@ -19,6 +19,7 @@
 
 #include <stdio.h>
 #include <sys/mman.h>
+#include <cutils/properties.h>
 
 #ifdef WITH_JIT
 #include <interp/Jit.h>
@@ -43,6 +44,24 @@ const char* startClassName = NULL;
 // called directoy by app_process
 ////////////////////////////////////////////////////////////
 
+void xposedInfo() {
+    char release[PROPERTY_VALUE_MAX];
+    char sdk[PROPERTY_VALUE_MAX];
+    char manufacturer[PROPERTY_VALUE_MAX];
+    char model[PROPERTY_VALUE_MAX];
+    char rom[PROPERTY_VALUE_MAX];
+
+    property_get("ro.build.version.release", release, "n/a");
+    property_get("ro.build.version.sdk", sdk, "n/a");
+    property_get("ro.product.manufacturer", manufacturer, "n/a");
+    property_get("ro.product.model", model, "n/a");
+    property_get("ro.build.display.id", rom, "n/a");
+
+    ALOGD("Starting Xposed binary version %s, compiled for SDK %d\n", XPOSED_VERSION, PLATFORM_SDK_VERSION);
+    ALOGD("Phone: %s (%s), Android version %s (SDK %s)\n", model, manufacturer, release, sdk);
+    ALOGD("ROM: %s\n", rom);
+}
+
 bool isXposedDisabled() {
     // is the blocker file present?
     if (access(XPOSED_LOAD_BLOCKER, F_OK) == 0) {

xposed.h

@@ -13,7 +13,7 @@ namespace android {
 #define XPOSED_CLASS "de/robv/android/xposed/XposedBridge"
 #define XPOSED_CLASS_DOTS "de.robv.android.xposed.XposedBridge"
 #define XRESOURCES_CLASS "android/content/res/XResources"
-#define XPOSED_VERSION "29"
+#define XPOSED_VERSION "30"
 
 #ifndef ALOGD
 #define ALOGD LOGD
@@ -26,6 +26,7 @@ extern bool keepLoadingXposed;
 typedef std::list<Method>::iterator XposedOriginalMethodsIt;
 
 // called directoy by app_process
+void xposedInfo();
 bool isXposedDisabled();
 bool xposedShouldIgnoreCommand(const char* className, int argc, const char* const argv[]);
 bool addXposedToClasspath(bool zygote);