Better INSTALL.md and Makefile rules

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

INSTALL.md

@@ -1,19 +1,32 @@
+## Compilation
+
+RocksDB's library should be able to compile without any dependency installed,
+although we recommend installing some compression libraries (see below).
+We do depend on newer gcc with C++11 support.
+
+There are few options when compiling RocksDB:
+
+* [recommended] `make static_lib` will compile librocksdb.a, RocksDB static library.
+
+* `make shared_lib` will compile librocksdb.so, RocksDB shared library.
+
+* `make check` will compile and run all the unit tests
+
+* `make all` will compile our static library, and all our tools and unit tests. Our tools
+depend on gflags. You will need to have gflags installed to run `make all`.
+
 ## Dependencies
 
-RocksDB is developed on Linux (CentOS release 5.2), with gcc 4.8.1.
-It depends on gcc with C++11 support.
-
-* RocksDB depends on the following libraries:
+* You can link RocksDB with following compression libraries:
   - [zlib](http://www.zlib.net/) - a library for data compression.
   - [bzip2](http://www.bzip.org/) - a library for data compression.
   - [snappy](https://code.google.com/p/snappy/) - a library for fast
       data compression.
-  - [gflags](https://code.google.com/p/gflags/) - a library that handles
-      command line flags processing.
 
-RocksDB will successfully compile without the compression libraries included,
-but some things may fail. We do not support releases without the compression
-libraries. You are on your own.
+* All our tools depend on:
+  - [gflags](https://code.google.com/p/gflags/) - a library that handles
+      command line flags processing. You can compile rocksdb library even
+      if you don't have gflags installed.
 
 ## Supported platforms
 
@@ -69,12 +82,3 @@ libraries. You are on your own.
 
 * **iOS**:
   * Run: `TARGET_OS=IOS make static_lib`
-
-## Compilation
-`make clean; make` will compile librocksdb.a (RocksDB static library) and all
-the unit tests. You can run all unit tests with `make check`.
-
-For shared library builds, exec `make shared_lib` instead.
-
-If you followed the above steps and your compile or unit tests fail,
-please submit an issue: (https://github.com/facebook/rocksdb/issues)

Makefile

@@ -14,12 +14,10 @@ else
 endif
 
 ifeq ($(MAKECMDGOALS),shared_lib)
-PLATFORM_SHARED_LDFLAGS=-fPIC
 OPT += -DNDEBUG
 endif
 
 ifeq ($(MAKECMDGOALS),static_lib)
-PLATFORM_SHARED_LDFLAGS=-fPIC
 OPT += -DNDEBUG
 endif
 
@@ -181,10 +179,6 @@ release:
 	$(MAKE) clean
 	OPT="-DNDEBUG -O2" $(MAKE) static_lib $(PROGRAMS) -j32
 
-release_shared_lib:
-	$(MAKE) clean
-	OPT="-DNDEBUG -O2" $(MAKE) shared_lib -j32
-
 coverage:
 	$(MAKE) clean
 	COVERAGEFLAGS="-fprofile-arcs -ftest-coverage" LDFLAGS+="-lgcov" $(MAKE) all check -j32
@@ -192,11 +186,11 @@ coverage:
 	# Delete intermediate files
 	find . -type f -regex ".*\.\(\(gcda\)\|\(gcno\)\)" -exec rm {} \;
 
-check: $(PROGRAMS) $(TESTS) $(TOOLS)
+check: $(TESTS) ldb
 	for t in $(TESTS); do echo "***** Running $$t"; ./$$t || exit 1; done
 	python tools/ldb_test.py
 
-ldb_tests: all $(PROGRAMS) $(TESTS) $(TOOLS)
+ldb_tests: ldb
 	python tools/ldb_test.py
 
 crash_test: whitebox_crash_test blackbox_crash_test

build_tools/build_detect_platform

@@ -184,12 +184,6 @@ if [ "$CROSS_COMPILE" = "true" -o "$FBCODE_BUILD" = "true" ]; then
     # Also don't need any compilation tests if compiling on fbcode
     true
 else
-    # do fPIC on 64 bit in non-fbcode environment
-    case "$TARGET_OS" in
-        x86_64)
-            PLATFORM_CXXFLAGS="$PLATFORM_CXXFLAGS -fPIC"
-    esac
-
     # If -std=c++0x works, use <atomic>.  Otherwise use port_posix.h.
     $CXX $CFLAGS -std=c++0x -x c++ - -o /dev/null 2>/dev/null  <<EOF
       #include <atomic>