PHP odbc driver as shared extension

I am using php with version 5.6.31 in embedded project with yocto-linux as operating system.What I wants to do is have odbc driver as shared library instead of hard-link. Reason for this is I have 2 different use-cases with use PHP with one requiring custom-odbc-driver.Since I am building it for embedded domain due to space concern I doesn't wants to add it statically in PHP binary.There is guide available to compile php extension as shared:

http://www.phpinternalsbook.com/build_system/building_extensions.html

My questing is can we have odbc driver as shared library? guide mentioned that not all but few extension can be shared. I tried building PHP with config flag --with-custom-odbc=shared but it failed with fatal error: odbc.h : No such file or directory .

--with-custom-odbc flag required path with odbc installation. If we can have odbc driver as shared library then which config flag should be used to describe it?

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