These simple changes are required to allow builds on ppc64[le] systems
consistent with X86. The Makefile now recognizes both ppc64 and ppc64le, and
in the absence of PORTABLE=1, the code will be built analogously to the X86
-march=native.

Note that although GCC supports -mcpu=native -mtune=native on POWER, it
doesn't work correctly on all systems. This is why we need to get the actual
machine model from the AUX vector.

Summary:
I see a lot of users compiling RocksDB with `make` or `make all` and then using those binaries in production. They end up running debug builds :(

This diff makes it harder for them:
1. I added an explicit warning to INSTALL.md
2. When you compile with `make all`, your resulting library will be librocksdb_debug.a
3. I also print out a warning when you compile in debug mode.

Hopefully should be enough :)

Test Plan: none

Reviewers: rven, yhchiang, kradhakrishnan, anthony, sdong, dhruba, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D48093

Summary: Fix broken gflags link

Test Plan: Follow the link

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D40503

Summary:
This diff changes compile to optimize for native platform by default. This will automatically turn on crc32 optimizations for modern processors, which greatly improves rocksdb's performance.

I also did some more changes to compilation documentation.

Test Plan:
compile with `make`, observe -march=native
compile with `PORTABLE=1 make`, observe no -march=native

Reviewers: sdong, rven, yhchiang, MarkCallaghan

Reviewed By: MarkCallaghan

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D30225

Summary: As tittle.

Test Plan: Not needed

Reviewers: MarkCallaghan, ljin, yhchiang, igor

Reviewed By: igor

Subscribers: rven, leveldb

Differential Revision: https://reviews.facebook.net/D24231

Summary: We have a lot of problems with gflags. However, when compiling rocksdb static library, we don't need gflags dependency. Reorganize INSTALL.md such that first-time customers don't need any dependency installed to actually build rocksdb static library.

Test Plan: none

Reviewers: dhruba, haobo

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D18501

Summary:
I had to make number of changes to the code and Makefile:
* Add `make lib`, that will create static library without debug info. We need this to avoid growing binary too much. Currently it's 14MB.
* Remove cpuinfo() function and use __SSE4_2__ macro. We actually used the macro as part of Fast_CRC32() function.
As a result, I also accidentally fixed this issue: https://www.facebook.com/groups/rocksdb.dev/permalink/549700778461774/?stream_ref=2
* Remove __thread locals in OS_MACOSX

Test Plan: `make lib PLATFORM=IOS`

Reviewers: ljin, haobo, dhruba, sdong

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17475

Summary: Replace "RocskDB" by "RocksDB" in INSTALL.md

Test Plan: No code change.

Reviewers: ljin, igor

Reviewed By: ljin

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16977

Added missing component : gflags in Linux platform.

Summary: Explained what it takes to compile it on linux.

Test Plan: -

Reviewers: dhruba, kailiu

Reviewed By: kailiu

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14151