Set TARGETPLATFORM=BUILD, idlc is for the build platform

It doesn't build yet when cross-compiling, though. It needs REGLIB,
SALLIB and SALHELPERLIB, and so far these get built only for the host
platform when cross-compiling.

Need to fix that. Can't have this ad-hoc mixing of build platform
tools and host platform libs in the same OUTDIR any more. When
cross-compiling we should do a full separation of binaries for build
and host. Libraries like SALLIB are needed for both.

idlc/source/makefile.mk

@@ -30,6 +30,7 @@ PRJ=..
 PRJNAME=idlc
 TARGET=idlc
 TARGETTYPE=CUI
+TARGETPLATFORM=BUILD
 LIBTARGET=NO
 
 ENABLE_EXCEPTIONS=TRUE

idlc/source/preproc/makefile.mk

@@ -30,6 +30,7 @@ PRJ=..$/..
 PRJNAME=idlc
 TARGET=idlcpp
 TARGETTYPE=CUI
+TARGETPLATFORM=BUILD
 
 # --- Settings -----------------------------------------------------