gm2-6.4.0 ignore LDFLAGS

[john o goyo]

Greetings, Gaius.

I am trying to build gcc+gm2-6.4.0-20181220 with gcc-6.3.0.  (The latter 
builds without problem.)

The build of gm2 fails at pg.  On Solaris, recv() and friends reside in 
the nsl and socket libraries.
These libraries were added to LDFLAGS but these flags are ignored in the 
build of ppg.

/home/build/gcc/6.3.0/bin/gcc -g -o gm2/pg gm2/gm2-pg-boot/Glibc.o 
gm2/gm2-pg-boot/Gmcrts.o gm2/gm2  g-boot/GUnixArgs.o 
gm2/gm2-pg-boot/GSelective.o gm2/gm2-pg-boot/Gtermios.o 
gm2/gm2-pg-boot/GSysExce  ions.o gm2/gm2-pg-boot/Gldtoa.o 
gm2/gm2-pg-boot/Gdtoa.o gm2/gm2-pg-boot/Gwrapc.o gm2/gm2-pg-boot/Gp  .o 
gm2/gm2-pg-boot/GSYSTEM.o gm2/gm2-pg-boot/Gerrno.o 
gm2/gm2-pg-boot/GSymbolKey.o gm2/gm2-pg-boot/  ameKey.o 
gm2/gm2-pg-boot/GLists.o gm2/gm2-pg-boot/Gbnflex.o 
gm2/gm2-pg-boot/GASCII.o gm2/gm2-pg-boo  GArgs.o  gm2/gm2-pg-boot/GFIO.o 
gm2/gm2-pg-boot/GStrIO.o gm2/gm2-pg-boot/GStrLib.o gm2/gm2-pg-boot/G  
dexing.o gm2/gm2-pg-boot/GStorage.o gm2/gm2-pg-boot/GDebug.o 
gm2/gm2-pg-boot/GIO.o gm2/gm2-pg-boot/  tdIO.o 
gm2/gm2-pg-boot/GM2EXCEPTION.o gm2/gm2-pg-boot/GStrCase.o 
gm2/gm2-pg-boot/GNumberIO.o gm2/gm  pg-boot/GAssertion.o 
gm2/gm2-pg-boot/GPushBackInput.o gm2/gm2-pg-boot/GSysStorage.o 
gm2/gm2-pg-boot  DynamicStrings.o gm2/gm2-pg-boot/GM2RTS.o 
gm2/gm2-pg-boot/GRTExceptions.o gm2/gm2-pg-boot/Gpg.o gm2  
m2-pg-boot/main.o -lm -lpth

(It also failed at ppg.)

If I run the above with -lnsl -lsocket added, pg builds (as did ppg with 
manually adding the libraries).

My question: What invokes the pg/ppg builds (so that I can manually add 
the libraries need)?

Sincerely,
john