mknative-gcc for GCC 12.3.0 on earmv4*, and powerpc64.

mknative-gcc for GCC 10 and almost all platforms. one of the
myriad of arm platforms, and the powerpc* platforms are not
yet done.

mknative-gcc for GCC 8.3 and all ports.

regen for earmv4 and GCC 7.

redo mknative-gcc for all ports. main changes include:
- "#define HAVE_CC_TLS 1" for most/all ports, thanks maya@
- "#define _GLIBCXX_HAVE_LDEXPL 1" and "#define _GLIBCXX_HAVE_TGMATH_H 1"
for many

redo mknative-gcc for all ports. main changes include:
- "#define HAVE_CC_TLS 1" for most/all ports, thanks maya@
- "#define _GLIBCXX_HAVE_LDEXPL 1" and "#define _GLIBCXX_HAVE_TGMATH_H 1"
for many ports
- arm64 and amd64 had a broken c++config.h that disabled many things
- configargs.h has more normalisation
- ppc64 has a few things fixed, must have missed several mknative rounds

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mknative gcc 6.4 and powerpc / earmv4. earmv4 seems to work.
powerpc not properly tested yet, but builds.

mknative bootstrap-libgcc GCC 5.3 for most arm platforms. having
minor issue with the next step.

regen minor bits for amd64.

merge GCC 4.8 build.