Can't use both RocksDB and Speedb at the same time

[ismailtzn]

Hello,

First of all, I appreciate the project. It is a very good solution that it is designed as a library that can be directly replaced instead of RocksDB. However, in a scenario where I need to use RocksDB in one project and Speedb in another project, one of the two applications stops working. While the RocksDB static library is installed on my system, the application that uses Speedb gives a Segmentation Fault. In the opposite case, the application developed with RocksDB gives an error while the Speedb static library is installed. It would be nice if we could customize the directories to be made for header and library installations in the Speedb installation for use in such and similar scenarios.