How to substitute a system header file with that included in the package?

To compile a certain package the file /usr/include/linux/swab.h should be substituted with another one. This is easy when compiling for home desktop but I cannot do that in OBS because it requires root priviledges.

What should I do to get the package build well?

¿? Simply use “-I” to specify where the new header is located. The original tarball should already be setup to do that…

Where tyo use -I? I tried to change CXXFLAGS variable, but this seem not to help.

In a place where “a certain package” looks at…