Set min ndk version to API 21 for armeabi-v7a and x86

[bitmold]

@eighthave I made this change regarding #140 - I believe these are set to 19 as a mistake. Orbot targets API 21 and for that matter tor browser for android sets this to 21 for each abi too

[bitmold]

Oh and yea, with NDK 26 these ABIs won't build if set to less than 21

[syphyr]

Mips NDK_PLATFORM_LEVEL should also be changed to 21 and minSdkVersion should be bumped to 21 in both build.gradle files.

I misunderstood the purpose of this PR. Please ignore.

[bitmold]

guardianproject/tor#6 is also necessary for building with NDK 26

[bitmold]

@syphyr after merging this I was able to build tor-android into Orbot targeting arm64-v8a and did not get the segmentation fault you had mentioned. With this PR merged as well as the PR i had made to the patched guardianproject/tor repo merged, you can build with the latest NDK LTS release.
@n8fr8 @uniqx @n8fr8

[syphyr]

@syphyr after merging this I was able to build tor-android into Orbot targeting arm64-v8a and did not get the segmentation fault you had mentioned. With this PR merged as well as the PR i had made to the patched guardianproject/tor repo merged, you can build with the latest NDK LTS release. @n8fr8 @uniqx @n8fr8

Strange, its still crashing for me.

05-14 03:02:29.222  3175  3214 E AndroidRuntime: FATAL EXCEPTION: tor
05-14 03:02:29.222  3175  3214 E AndroidRuntime: Process: org.torproject.android, PID: 3175
05-14 03:02:29.222  3175  3214 E AndroidRuntime: java.lang.UnsatisfiedLinkError: No implementation found for void org.torproject.jni.TorService.mainConfigurationFree() (tried Java_org_torproject_jni_TorService_mainConfigurationFree and Java_org_torproject_jni_TorService_mainConfigurationFree__)
05-14 03:02:29.222  3175  3214 E AndroidRuntime: 	at org.torproject.jni.TorService.mainConfigurationFree(Native Method)
05-14 03:02:29.222  3175  3214 E AndroidRuntime: 	at org.torproject.jni.TorService.-$$Nest$mmainConfigurationFree(TorService.java)
05-14 03:02:29.222  3175  3214 E AndroidRuntime: 	at org.torproject.jni.TorService$3.run(TorService.java:385)

which NDK are you using? This was with 26d.

The size of libtor.so is much smaller than usual. Orbot still builds and starts, but it crashes as soon as I try to connect. When I try to grep for the jni functions in libtor.so, they are not there when building with NDK 26.