testsuite: Fix analyzer errors for newlib-fd

testsuite: Fix analyzer errors for newlib-fd

Investigating analyzer testsuite errors for cris-elf.  The same are
seen for pru-elf according to posts to gcc-testresults@.

The test fd-access-mode-target-headers.c uses the analyzer
"sm-fd" which for this use requires (e.g.) that constants
O_ACCMODE, O_RDONLY and O_WRONLY are defined as literal
constants.  While for glibc, O_ACCMODE is defined as:
 #define O_ACCMODE 0003
in newlib, it's defined as:
 #define O_ACCMODE (O_RDONLY|O_WRONLY|O_RDWR)
and the analyzer is not able to make use of an expression
like this (even though O_RDONLY, O_WRONLY and O_RDWR are
defined as literal constants and the whole evaluates to 3).
Better do as for AIX and skip this test.

testsuite:
	* gcc.dg/analyzer/fd-access-mode-target-headers.c: Skip for
	newlib targets too.