[bazel][libc] Remove target compatibility restrictions for float128 (#169292)

The restrictions here aren't nearly as much about the OS as the compiler
and architecture, but the Bazel restriction was OS-based. Everything
seems to work well on even Arm64 macOS, and I would expect most BSDs and
other OSes to work well with Clang's support on x86-64.

The source code here already handles detecting when there is compiler
support for the type. And the users of this don't `select` or do
anything else to conditionally include the header, so it seems better to
not restrict access to the header from the build system, and instead
continue making the source code compatible or a no-op on relevant
configurations.

Author: chandlerc

utils/bazel/llvm-project-overlay/libc/BUILD.bazel

@@ -171,11 +171,6 @@ libc_support_library(
 libc_support_library(
     name = "llvm_libc_types_float128",
     hdrs = ["include/llvm-libc-types/float128.h"],
-    target_compatible_with = select({
-        "@platforms//os:linux": [],
-        "@platforms//os:windows": [],
-        "//conditions:default": ["@platforms//:incompatible"],
-    }),
     deps = [":llvm_libc_macros_float_macros"],
 )