android: raise minSdkVersion to 21

The number of MPD installs on Android < 5.0 is negligible, and that
API version introduces lots of useful features for MPD.

Makefile.am

@@ -294,7 +294,7 @@ libmpd.so: $(filter %.a,$(src_mpd_LDADD)) libmain.a
 	$(AM_V_CXXLD)$(CXXLD) -shared -Wl,--no-undefined,-shared,-Bsymbolic -llog -lz -o $@ $(AM_CXXFLAGS) $(CXXFLAGS) $(LDFLAGS) src/libmain_a-Main.o $(src_mpd_LDADD) $(LIBS)
 
 ANDROID_SDK_BUILD_TOOLS_VERSION = 27.0.0
-ANDROID_SDK_PLATFORM = android-17
+ANDROID_SDK_PLATFORM = android-21
 
 ANDROID_BUILD_TOOLS_DIR = $(ANDROID_SDK)/build-tools/$(ANDROID_SDK_BUILD_TOOLS_VERSION)
 ANDROID_SDK_PLATFORM_DIR = $(ANDROID_SDK)/platforms/$(ANDROID_SDK_PLATFORM)

android/AndroidManifest.xml

@@ -5,7 +5,7 @@
           android:versionCode="20"
           android:versionName="0.20.21">
 
-  <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="17"/>
+  <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="21"/>
 
   <application android:icon="@drawable/icon" android:label="@string/app_name">
     <activity android:name=".Main"

android/build.py

@@ -65,7 +65,7 @@ class AndroidNdkToolchain:
         self.build_path = build_path
 
         ndk_arch = abi_info['ndk_arch']
-        android_api_level = '14'
+        android_api_level = '21'
         ndk_platform = 'android-' + android_api_level
 
         # select the NDK compiler

android/src/Main.java

@@ -49,7 +49,7 @@ public class Main extends Activity implements Runnable {
 			TextView tv = new TextView(this);
 			tv.setText("Failed to load the native MPD libary.\n" +
 				   "Report this problem to us, and include the following information:\n" +
-				   "ABI=" + Build.CPU_ABI + "\n" +
+				   "SUPPORTED_ABIS=" + String.join(", ", Build.SUPPORTED_ABIS) + "\n" +
 				   "PRODUCT=" + Build.PRODUCT + "\n" +
 				   "FINGERPRINT=" + Build.FINGERPRINT + "\n" +
 				   "error=" + Loader.error);

src/input/plugins/FileInputPlugin.cxx

@@ -65,12 +65,9 @@ OpenFileInputStream(Path path,
 		throw FormatRuntimeError("Not a regular file: %s",
 					 path.c_str());
 
-#if !defined(__BIONIC__) || __ANDROID_API__ >= 21
-	/* posix_fadvise() requires Android API 21 */
 #ifdef POSIX_FADV_SEQUENTIAL
 	posix_fadvise(reader.GetFD().Get(), (off_t)0, info.GetSize(),
 		      POSIX_FADV_SEQUENTIAL);
-#endif
 #endif
 
 	return InputStreamPtr(new FileInputStream(path.ToUTF8().c_str(),

src/system/EPollFD.cxx

@@ -22,21 +22,6 @@
 #include "EPollFD.hxx"
 #include "FatalError.hxx"
 
-#if defined(__BIONIC__) && __ANDROID_API__ < 21
-
-#include <sys/syscall.h>
-#include <fcntl.h>
-
-#define EPOLL_CLOEXEC O_CLOEXEC
-
-static inline int
-epoll_create1(int flags)
-{
-    return syscall(__NR_epoll_create1, flags);
-}
-
-#endif
-
 EPollFD::EPollFD()
 	:fd(::epoll_create1(EPOLL_CLOEXEC))
 {