CMake: Read rocksdb version from version.h header file

Summary:
This replaces reading the rocksdb version by external shell script. This does not work reliably on Windows (I wander how it works on AppVeyor).
Closes https://github.com/facebook/rocksdb/pull/3737

Differential Revision: D7703106

Pulled By: ajkr

fbshipit-source-id: 4079c7c77431757e9ddc801363ed896b18fdbf23

CMakeLists.txt

@@ -132,19 +132,17 @@ endif()
 
 string(REGEX REPLACE "[^0-9a-f]+" "" GIT_SHA "${GIT_SHA}")
 
-set(SH_CMD "sh")
-execute_process(COMMAND
-  ${SH_CMD} -c "build_tools/version.sh full"
-  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-  OUTPUT_VARIABLE ROCKSDB_VERSION
-)
-string(STRIP "${ROCKSDB_VERSION}" ROCKSDB_VERSION)
-execute_process(COMMAND
-  ${SH_CMD} -c "build_tools/version.sh major"
-  WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
-  OUTPUT_VARIABLE ROCKSDB_VERSION_MAJOR
-)
-string(STRIP "${ROCKSDB_VERSION_MAJOR}" ROCKSDB_VERSION_MAJOR)
+
+# Read rocksdb version from version.h header file.
+file(READ include/rocksdb/version.h version_header_file)
+string(REGEX MATCH "#define ROCKSDB_MAJOR ([0-9]+)" _ ${version_header_file})
+set(ROCKSDB_VERSION_MAJOR ${CMAKE_MATCH_1})
+string(REGEX MATCH "#define ROCKSDB_MINOR ([0-9]+)" _ ${version_header_file})
+set(ROCKSDB_VERSION_MINOR ${CMAKE_MATCH_1})
+string(REGEX MATCH "#define ROCKSDB_PATCH ([0-9]+)" _ ${version_header_file})
+set(ROCKSDB_VERSION_PATCH ${CMAKE_MATCH_1})
+set(ROCKSDB_VERSION ${ROCKSDB_VERSION_MAJOR}.${ROCKSDB_VERSION_MINOR}.${ROCKSDB_VERSION_PATCH})
+
 
 option(WITH_MD_LIBRARY "build with MD" ON)
 if(WIN32 AND MSVC)