size_t not declared in this scope

[M3T00]

on raspberry pi 4 with raspios bullseye - after - clone - sh autogen.sh - ./configure - then make throws these errors:

CXX src/zimg/colorspace/libzimg_internal_la-matrix3.lo
src/zimg/colorspace/matrix3.cpp: In function ‘zimg::colorspace::Vector3 zimg::colorspace::operator*(const zimg::colorspace::Vector3&, const zimg::colorspace::Vector3&)’:
src/zimg/colorspace/matrix3.cpp:20:7: error: ‘size_t’ was not declared in this scope; did you mean ‘std::size_t’?
20 | for (size_t i = 0; i < 3; ++i) {
| ^~~~~~
| std::size_t
In file included from /usr/include/c++/10/utility:68,
from /usr/include/c++/10/array:38,
from src/zimg/colorspace/matrix3.h:6,
from src/zimg/colorspace/matrix3.cpp:1:
/usr/include/arm-linux-gnueabihf/c++/10/bits/c++config.h:264:26: note: ‘std::size_t’ declared here
264 | typedef SIZE_TYPE size_t;
| ^~~~~~
truncated - throws several other errors in for loops see attached file
zimgerror.txt