In C++17 the out-of-class definitions for static constexpr variables are
redundant, because they are implicitly inline. This change avoids
"redundant redeclaration" warnings from -Wsystem-headers -Wdeprecated.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>

libstdc++-v3/ChangeLog:

	* include/bits/random.tcc (linear_congruential_engine): Do not
	define static constexpr members when they are implicitly inline.
	* include/std/ratio (ratio, __ratio_multiply, __ratio_divide)
	(__ratio_add, __ratio_subtract): Likewise.
	* include/std/type_traits (integral_constant): Likewise.
	* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
	line number.

Tested powerpc64le-linux. Committed to trunk.