compat: remove memcpy -> memmove backwards compatibility alias

In glib 2.13 memcpy was changed such that the way it copied bytes was reversed.
This caused all sorts of issues for existing software, which depended on the
existing behavior (when they should have been using memmove). See:
https://sourceware.org/bugzilla/show_bug.cgi?id=12518
https://bugzilla.redhat.com/show_bug.cgi?id=638477

Now that we require glibc 2.17+ (#17538), we should be well clear of having to
maintain our memcpy ->  memmove aliasing, which was introduced in #4339.

Author: fanquake

src/Makefile.am

@@ -553,7 +553,6 @@ libbitcoin_util_a_SOURCES = \
   support/lockedpool.cpp \
   chainparamsbase.cpp \
   clientversion.cpp \
-  compat/glibc_sanity.cpp \
   compat/glibcxx_sanity.cpp \
   compat/strnlen.cpp \
   fs.cpp \

src/compat/glibc_compat.cpp

@@ -9,13 +9,6 @@
 #include <cstddef>
 #include <cstdint>
 
-// Prior to GLIBC_2.14, memcpy was aliased to memmove.
-extern "C" void* memmove(void* a, const void* b, size_t c);
-extern "C" void* memcpy(void* a, const void* b, size_t c)
-{
-    return memmove(a, b, c);
-}
-
 #if defined(__i386__) || defined(__arm__)
 
 extern "C" int64_t __udivmoddi4(uint64_t u, uint64_t v, uint64_t* rp);

src/compat/glibc_sanity.cpp

@@ -5,7 +5,6 @@
 #ifndef BITCOIN_COMPAT_SANITY_H
 #define BITCOIN_COMPAT_SANITY_H
 
-bool glibc_sanity_test();
 bool glibcxx_sanity_test();
 
 #endif // BITCOIN_COMPAT_SANITY_H

src/compat/sanity.h

@@ -771,7 +771,7 @@ static bool InitSanityCheck()
         return InitError(Untranslated("Elliptic curve cryptography sanity check failure. Aborting."));
     }
 
-    if (!glibc_sanity_test() || !glibcxx_sanity_test())
+    if (!glibcxx_sanity_test())
         return false;
 
     if (!Random_SanityCheck()) {

src/init.cpp

@@ -13,7 +13,6 @@ BOOST_FIXTURE_TEST_SUITE(sanity_tests, BasicTestingSetup)
 
 BOOST_AUTO_TEST_CASE(basic_sanity)
 {
-  BOOST_CHECK_MESSAGE(glibc_sanity_test() == true, "libc sanity test");
   BOOST_CHECK_MESSAGE(glibcxx_sanity_test() == true, "stdlib sanity test");
   BOOST_CHECK_MESSAGE(ECC_InitSanityCheck() == true, "secp256k1 sanity test");
   BOOST_CHECK_MESSAGE(ChronoSanityCheck() == true, "chrono epoch test");