libstdc++: Annotate most lambdas with always_inline

libstdc++: Annotate most lambdas with always_inline

All of the annotated lambdas are simply a necessary means for
implementing these functions and should never result in an actual
function call. Many of these lambdas would go away if C++ had better
language support for packs.

Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:

	PR libstdc++/108030
	* include/experimental/bits/simd_detail.h: Define
	_GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA.
	* include/experimental/bits/simd.h: Annotate lambdas with
	_GLIBCXX_SIMD_ALWAYS_INLINE_LAMBDA.
	* include/experimental/bits/simd_builtin.h: Ditto.
	* include/experimental/bits/simd_converter.h: Ditto.
	* include/experimental/bits/simd_fixed_size.h: Ditto.
	* include/experimental/bits/simd_math.h: Ditto.
	* include/experimental/bits/simd_neon.h: Ditto.
	* include/experimental/bits/simd_x86.h: Ditto.