Some settings in nmake.local are overwriten in nmake.opt

[pmeems]

I've created a nmake.local file so we don't need to change the GDAL files every time. This seems to be working fine except for the DLLBUILD settings. This setting is set in nmake.opt to 1, but we want to set it to 0. Because nmake.local is called at the beginning my setting is overwritten.

Solution is to check if the setting is already set, like it is done with other settings: Change line 171 DLLBUILD=1 to !IFNDEF DLLBUILD DLLBUILD=1 !ENDIF

Other settings might benefit from similar changes, like STDCALL, PAM_SETTING and INCLUDE_OGR_FRMTS

[Jukka Rahkonen]

This sounds reasonable for me but you must raise the attention of some developer with commit rights. I suggest to make a patch, attach it to this ticket, and edit the summary to begin with [PATCH]...

[Even Rouault]

In 41758:

nmake.opt: avoid some settings to be defined unconditionnaly (fixes #5286)