Could not build generate_color_test_pattern on macOS

[bgschunck]

Many warnings when trying to build generate_color_test_pattern, but file_map.cpp results in 8 compiler errors that appear to be problems in the code, hard to be sure. The errors arise from deep in the STL.

Using Apple clang version 11.0.3 (clang-1103.0.32.62)
Target: x86_64-apple-darwin19.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

See attached log from the builds:

build-errors.txt