The win32 build system does not generate config.h and correctly runs
the compiler without defining HAVE_CONFIG_H. Nevertheless some files
include config.h without checking for its availability, breaking the
build from a clean directory:
test\utils.h(2) : fatal error C1083: Cannot open include file:
'config.h': No such file or directory
...
Adding scaling-helpers-test to the testsuite on win32 makes MSVC
complain about int64_t being used as an expression:
scaling-helpers-test.c(27) : error C2275: 'int64_t' : illegal use of
this type as an expression
Individual correctness check for the new bilinear scaling related
supplementary function. This test program uses a bit wider range
of input arguments, not covered by other tests.
