exfat: support to build some exfat tools on Android.

[leeminghao]

Now, add support to build mkexfatfs, exfatfsck, dumpexfat and exfatlabel

Change-Id: I9856f087157fde528e999dab316ede1662ba5b67
Signed-off-by: liminghao liminghao@xiaomi.com

[relan]

Great! I've created a feature branch android, that will eventually merge into develop and master.

Is there anything else related to Android support that needs to be changed? E.g. here are some modifications by LineageOS:

• Handle 64-bit offsets correctly on Android
• exfat-fuse: Don't export UTF conversion functions

[leeminghao]

I'm sorry! For Android, the change "Handle 64-bit offsets correctly on Android" is not neccessary, because the bionic will automatic select to lseek/pread/pwrite. We just need control __USE_FILE_OFFSET64 according to _FILE_OFFSET_BITS defined into config.h

#if defined(__USE_FILE_OFFSET64)
163extern int truncate(const char *, off_t) __RENAME(truncate64);
164extern off_t lseek(int, off_t, int) __RENAME(lseek64);
165extern ssize_t pread(int, void *, size_t, off_t) __RENAME(pread64);
166extern ssize_t pwrite(int, const void *, size_t, off_t) __RENAME(pwrite64);
167extern int ftruncate(int, off_t) __RENAME(ftruncate64);
168#else
169extern int truncate(const char *, off_t);
170extern off_t lseek(int, off_t, int);
171extern ssize_t pread(int, void *, size_t, off_t);
172extern ssize_t pwrite(int, const void *, size_t, off_t);
173extern int ftruncate(int, off_t);
174#endif

[relan]

OK.

Feel free to submit any other changes you would like to upstream.

[relan]

@leeminghao, do you mind my changing the license of Android.mk from Apache to GPLv2+? The whole project is under GPL, so it makes little sense to use a different license for a makefile.

[leeminghao]

I accept to change the license to GPLv2+