Fixes GCC 8 warnings:
dll/opengl/glu32/src/libnurbs/internals/subdivider.cc:852:2: error: this 'if' clause does not guard... [-Werror=misleading-indentation]
if( jarc->pwlArc ) jarc->pwlArc->deleteMe( pwlarcpool ); jarc->pwlArc = 0;
^~
dll/opengl/glu32/src/libnurbs/internals/subdivider.cc:852:59: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
if( jarc->pwlArc ) jarc->pwlArc->deleteMe( pwlarcpool ); jarc->pwlArc = 0;
^~~~
There is no need to compile our DLLs as shared libraries since we are
managing symbols exports and imports through spec files.
On my system, this reduces the configure-time by a factor of two.
