Build on Android error in default

>> Issue 1
Currently I have the error at the buid:
thread/qthread_unix.cpp:586:49: error: 'PTHREAD_INHERIT_SCHED' was not declared in this scope
pthread_attr_setinheritsched(&attr, PTHREAD_INHERIT_SCHED);

And sure, LibC (Bionic) has not got the function at all on any NDK version. For my project I had to use the definition checking:

#if !defined(_ANDROID_)
pthread_attr_setinheritsched(pthr_attr, PTHREAD_EXPLICIT_SCHED);
#endif

>> Issue 2
Also I have building errors for io/qfilesystemengine.cpp:
io/qfilesystemengine.cpp:295:52: error: 'const struct stat' has no member named 'st_mtim'
modificationTime_ = timespecToMSecs(statBuffer.st_mtim);
^
io/qfilesystemengine.cpp:296:48: error: 'const struct stat' has no member named 'st_ctim'
creationTime_ = timespecToMSecs(statBuffer.st_ctim);
^
io/qfilesystemengine.cpp:299:46: error: 'const struct stat' has no member named 'st_atim'
accessTime_ = timespecToMSecs(statBuffer.st_atim);

And seems the structure "stat" some different here for the fields "st_

time[_nsec]".

>> Issue 3
io/qfilesystemengine_unix.cpp: In static member function 'static QString QFileSystemEngine::resolveGroupName(uint)':
io/qfilesystemengine_unix.cpp:400:69: error: 'getgrgid_r' was not declared in this scope
if (!getgrgid_r(groupId, &entry, buf.data(), buf.size(), &gr)

>> Issue 4
extract.cpp: In function '_jintArray* Java_org_qtproject_qt5_android_ExtractStyle_extractChunkInfo(JNIEnv*, jobject, jbyteArray)':
extract.cpp:68:41: error: 'alloca' was not declared in this scope
void* storage = alloca(chunkSize);
^
extract.cpp: In function '_jintArray* Java_org_qtproject_qt5_android_ExtractStyle_extractChunkInfo20(JNIEnv*, jobject, jbyteArray)':
extract.cpp:157:37: error: 'alloca' was not declared in this scope
void* storage = alloca(chunkSize);

>> Issue 5
NEON mostly missed on Android, into the library GLESv2 of the NDK, include ARM_ARCH_7A, then dsp/dsp.h is wrong about WEBP_ANDROID_NEON definition. Symbol VP8DspInitNEON, for example, has missed everywhere.