compiling glib20 in ports with gcc v4.6.2

[b. f.]

> .if !empty(.CURDIR:M/usr/ports/*) && exists(/usr/local/bin/gcc46)
> CC=gcc46
> CXX=g++46
> CPP=cpp46
> CFLAGS+=-mssse3
> CPUTYPE?=core2
> LD=/usr/local/bin/ld
> .endif

Just use USE_GCC=4.6 with your cpu-specific additions to CFLAGS, and
the latest patch from PR ports/155201, it will be easier.  As it is,
you are missing all of the other devel/binutils utilities that are set
by USE_BINUTILS (which is implied by USE_GCC=4.6); the important
additions to the CFLAGS and LDFLAGS in bsd.gcc.mk that will point the
resulting binaries to the libraries in /usr/local/lib/gcc46, rather
than the older incompatible ones with identical names and major
version numbers in the base system; and the registering of lang/gcc46
as a runtime dependency in the package database.

Also, as you have seen, it is a known, long-standing problem with
ports that use devel/libtool, that they will often break if
devel/libtool is not built with the same compiler and toolchain as the
port.  A simple, although not very convenient, way to fix this is to
rebuild devel/libtool with appropriate compiler before building such
ports (although, in your case, you will have to ensure that
devel/libtool is not always built with USE_GCC=4.6, or you will break
your package accounting system with circular dependencies). A proper
solution is more complicated, involving either a
substantially-modified libtool, or separate per-compiler libtool
ports, or rebuilding a temporary libtool during the build of each port
that uses it.  Such a solution may be introduced into Ports as we
prepare for wider use of multiple compilers and toolchains, but for
now you will have to work around the problem.

b.