This is TBLD's default environment when GMP is built 64-bit. It may not help you but might.
env CFLAGS=' -O1 -march=x86-64 -mtune=core2 -I/usr/local/comp64/include -I/
usr/local/comp64/usr/include -I/usr/include -std=gnu89 ' CPPFLAGS=' -I/usr/lo
cal/comp64/include -I/usr/local/comp64/usr/include -I/usr/include -std=gnu89 '
CVSROOT=/root/cvs CXXFLAGS=' -O1 -march=x86-64 -mtune=core2 -I/usr/local/c
omp64/include -I/usr/local/comp64/usr/include -I/usr/include -std=gnu++98' EL
VISGUI=termcap HOME=src HOSTTYPE=i386 LANG=C LANGUAGE=C LC_ALL=C LDFLAGS=' -L/us
r/local/comp64/lib64 -L/usr/local/comp64/usr/lib64 -L/usr/local/comp64/lib -L/us
r/local/comp64/usr/lib' LOCALE=C LOGNAME=root MACHTYPE=i386-pc-linux-gnu MAKE2=m
ake MAKE2i=make OSTYPE=linux-gnu PATH=/usr/local/comp64/sbin:/usr/local/comp64/u
sr/sbin:/usr/local/comp64/sbin:/usr/local/comp64/usr/sbin:/usr/local/app64/sbin:
/usr/local/app64/usr/sbin:/sbin:/usr/sbin:/usr/local/sbin:/usr/local/usr/sbin:/u
sr/local/comp64/bin:/usr/local/comp64/usr/bin:/usr/local/comp64/usr/local/bin:/u
sr/local/comp64/bin:/usr/local/comp64/usr/bin:/usr/local/comp64/usr/local/bin:/u
sr/local/app64/bin:/usr/local/app64/usr/bin:/usr/local/app64/usr/local/bin:/bin:
/usr/bin:/usr/local/bin:/usr/local/musl/bin PKG_CONFIG_PATH=/usr/local/comp64/li
b64/pkgconfig:/usr/local/app64/share/pkgconfig POSIXLY_CORRECT=y PWD=/usr/local/
src9 SHELL=/bin/sh SHELLOPTS=braceexpand:hashall:interactive-comments
osix TERM
=xterm TERMCAP=/etc/termcap TTY=/dev/ttyp1 UNAME=Linux USER=src USER2_PATH=/usr/
local/comp64/sbin:/usr/local/comp64/usr/sbin:/usr/local/comp64/sbin:/usr/local/c
omp64/usr/sbin:/usr/local/app64/sbin:/usr/local/app64/usr/sbin:/sbin:/usr/sbin:/
usr/local/sbin:/usr/local/usr/sbin:/usr/local/comp64/bin:/usr/local/comp64/usr/b
in:/usr/local/comp64/usr/local/bin:/usr/local/comp64/bin:/usr/local/comp64/usr/b
in:/usr/local/comp64/usr/local/bin:/usr/local/app64/bin:/usr/local/app64/usr/bin
:/usr/local/app64/usr/local/bin:/bin:/usr/bin:/usr/local/bin:/usr/local/musl/bin
\
./configure --prefix=/usr/local/comp64 --exec-prefix=/usr/local/comp64 --datar
ootdir=/usr/local/comp64/share --datadir=/usr/local/comp64/share --sysconfdir=/u
sr/local/comp64/etc --libdir=/usr/local/comp64/lib64 --with-gnu-ld $* 2>&1 >>
build.configure.log 2>&1
exit
# /lib64:/usr/lib64:/usr/local/comp64/lib64:/usr/local/comp64/usr/lib64:/usr/loc
al/app64/lib64:/usr/local/app64/usr/lib64:/usr/local/lib64:/usr/local/usr/lib64:
/lib:/usr/lib:/usr/local/comp64/lib:/usr/local/comp64/usr/lib:/usr/local/app64/l
ib:/usr/local/app64/usr/lib:/usr/local/lib:/usr/local/usr/lib