mgr/Conscript-standard: fix build of StarVMC/StarGeometry with ROOT6 that doesn't ship ttables

[veprbl]

rootcint -f .sl73_x8664_gcc485/obj/StarVMC/StarGeometry/StarGeo_Cint.cxx -c .sl73_x8664_gcc485/obj/StarVMC/StarGeometry/StarGeo.h StarVMC/Geomet
ry/StarGeoLinkDef.h
In file included from input_line_9:3:
./.sl73_x8664_gcc485/obj/StarVMC/StarGeometry/StarGeo.h:949:10: fatal error: 'TDataSet.h' file not found
#include "TDataSet.h"
         ^~~~~~~~~~~~
Error: rootcint: compilation failure (.sl73_x8664_gcc485/obj/StarVMC/StarGeometry/StarGeo_Cint3c991d560d_dictUmbrella.h)
cons: *** [.sl73_x8664_gcc485/obj/StarVMC/StarGeometry/StarGeo_Cint.cxx] Error 1
cons: errors constructing .sl73_x8664_gcc485/obj/StarVMC/StarGeometry/StarGeo_Cint.h

[klendathu2k]

Remind me what %_IFLAGS adds to the command? The path to the exported include files?

[veprbl]

This is an arbitrary name that is set $env->{_IFLAGS}. Specifically, it is _IFLAGS because that was in a snippet I found inside the cons itself. There is at least one another existing piece of code that does the same thing, but the logic is quite spread:

star-sw/mgr/Conscript-standard

Lines 1241 to 1243 in eae2c00

	my $ROOTCINT_CPP =
	$INCLUDE . $main::PATH_SEPARATOR . $INCLUDE . "/tables";
	$ROOTCINT_CPP .= $main::PATH_SEPARATOR . $env1->{ENV}->{ROOTSRC};

star-sw/mgr/Conscript-standard

Lines 1255 to 1257 in eae2c00

	my $cscanner =
	find scan::cpp( $env1->{_cwd}, $ROOTCINT_CPP );
	my $ROOTCINT_CPPPATH = $cscanner->iflags($env3); #print "ROOTCINT_CPPPATH = $ROOTCINT_CPPPATH\n"; die;

star-sw/mgr/Conscript-standard

Lines 1309 to 1310 in eae2c00

	Command $env3 [ ($idlCintC , $idlCintH) ], @Deps,
	qq (rootcint -f %> -c $ROOTCINT_CPPPATH -D__ROOT__ %1 %2);

[klendathu2k]

Looking at the output of the tests... it looks like this is just appending the path to the include files (and a few other search paths as well). Looks good to me.