1.39.0 release

Bug fixes:
- build: use user-supplied CROSS_COMPILE in compiler check
- check-environment: add fuse3 detection and cross pkg-config fallback
- test: add test for missing user-supplied CROSS_COMPILE
- check-environment: fix fuse3 test program
- check-environment: fix fuse3 test on 32-bit architectures

Container images:
- docker: fix native pkg-config after foreign-arch install
- docker: skip equivs package when real cross compiler is installed