Revert "Add valgrind suppressions for wcsrtombs optimizations"

This reverts commit d3bbc4b96a.

Per discussion, it's not desirable to add valgrind suppressions for
outside our own code base (e.g. glibc in this case), especially when
the suppressions may be platform-specific. There are better ways to
deal with that, e.g. by providing local suppressions.

Discussion: https://www.postgresql.org/message-id/flat/90ac0452-e907-e7a4-b3c8-15bd33780e62%402ndquadrant.com

src/tools/valgrind.supp

@@ -212,39 +212,3 @@
    Memcheck:Cond
    fun:PyObject_Realloc
 }
-
-# wcsrtombs uses some clever optimizations internally, which to valgrind
-# may look like access to uninitialized data. For example AVX2 instructions
-# load data in 256-bit chunks, irrespectedly of wchar length. gconv does
-# somethink similar by loading data in 32bit chunks and then shifting the
-# data internally. Neither of those actually uses the uninitialized part
-# of the buffer, as far as we know.
-#
-# https://www.postgresql.org/message-id/90ac0452-e907-e7a4-b3c8-15bd33780e62@2ndquadrant.com
-
-{
-   wcsnlen_optimized
-   Memcheck:Cond
-   ...
-   fun:wcsrtombs
-   fun:wcstombs
-   fun:wchar2char
-}
-
-{
-   wcsnlen_optimized_addr32
-   Memcheck:Addr32
-   ...
-   fun:wcsrtombs
-   fun:wcstombs
-   fun:wchar2char
-}
-
-{
-   gconv_transform_internal
-   Memcheck:Cond
-   fun:__gconv_transform_internal_utf8
-   fun:wcsrtombs
-   fun:wcstombs
-   fun:wchar2char
-}