c/float_asm: support ARM soft floating point
c/float_asm: support ARM soft floating point

Using "armel" port forbids using VFP instructions. According to
https://wiki.debian.org/ArmEabiPort, the right way to detect VFP
support is:

    #if (defined(__VFP_FP__) && !defined(__SOFTFP__))

Otherwise, gcc built-ins defined in
https://gcc.gnu.org/onlinedocs/gcc-4.0.4/gccint/Soft-float-library-routines.html
and
https://chromium.googlesource.com/chromiumos/third_party/gcc/+/009f97f2bf0e7c070fac2d2806af05e166ceaf3c/gcc/gcc-4.6.0/libgcc/config/arm/sfp-machine.h
can be used, but their symbols are not defined directly.

fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared