With commit 7c6066b (pixman-private: include <float.h> only in C code) running `./autogen.sh && ./configure && make -j` shows the warning below.

```
[…]
  CC       lowlevel-blt-bench.o
  CC       check-formats.o
  CC       glyph-test.o
  CC       affine-test.o
  CC       radial-perf-test.o
  CC       affine-bench.o
  CC       scaling-bench.o
  CC       composite.o
  CC       cover-test.o
  CC       stress-test.o
  CC       scaling-helpers-test.o
lowlevel-blt-bench.c: In function ‘bench_L’:
lowlevel-blt-bench.c:183:18: warning: variable ‘qx’ set but not used [-Wunused-but-set-variable]
     volatile int qx;
                  ^
[…]
```