[coreboot] problems with kgpe-d16

[Ian Kelling]

1. building 4.6 gives build error

$ make crossgcc-x64 BUILDGCC_OPTIONS=-b CPUS=16
$ make

...

HOSTCC     cbfstool/lz4hc.o
    HOSTCC     cbfstool/lz4frame.o
/nocow/t/coreboot-4.6/util/cbfstool/lz4/lib/lz4frame.c: In function 'LZ4F_decompress':
/nocow/t/coreboot-4.6/util/cbfstool/lz4/lib/lz4frame.c:1092:33: error: this statement may fall through [-Werror=implicit-fallthrough=]
                 dctxPtr->dStage = dstage_storeHeader;
                 ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/nocow/t/coreboot-4.6/util/cbfstool/lz4/lib/lz4frame.c:1095:9: note: here
         case dstage_storeHeader:
         ^~~~
cc1: all warnings being treated as errors
util/cbfstool/Makefile.inc:133: recipe for target 'build/util/cbfstool/lz4frame.o' failed
make: *** [build/util/cbfstool/lz4frame.o] Error 1

2. built from git master (588ccaa9), crossgcc without -b this time as
the build didn't complain about it. seabios doesn't detect my hard
drive. I have an older coreboot seabios build that does, so it's
probably a software issue.

3. building 4.5 gives build error

configure: error: Building GCC requires GMP 4.2+, MPFR 2.4.0+ and MPC 0.8.0+.
Try the --with-gmp, --with-mpfr and/or --with-mpc options to specify
their locations.

I can probably figure that out but if someone knows off the top of their
head.