Add debug symbols to Android release

[louwers]

Fixes #2282 (hopefully).

 % tar -tvf build/debug-symbols.tar.gz
drwxr-xr-x  0 bart   staff       0 Apr 18 17:24 ./
drwxr-xr-x  0 bart   staff       0 Apr 18 17:24 ./armeabi-v7a/
drwxr-xr-x  0 bart   staff       0 Apr 18 17:24 ./x86/
drwxr-xr-x  0 bart   staff       0 Apr 18 17:24 ./arm64-v8a/
drwxr-xr-x  0 bart   staff       0 Apr 18 17:24 ./x86_64/
-rw-r--r--  0 bart   staff 193393432 Apr 18 17:24 ./x86_64/libmaplibre.so
-rw-r--r--  0 bart   staff 200794312 Apr 18 17:24 ./arm64-v8a/libmaplibre.so
-rw-r--r--  0 bart   staff 171135888 Apr 18 17:24 ./x86/libmaplibre.so
-rw-r--r--  0 bart   staff 172496144 Apr 18 17:24 ./armeabi-v7a/libmaplibre.so