CryptoPkg/Crt: import "inet_pton.c" (CVE-2019-14553)

For TianoCore BZ#1734, StdLib has been moved from the edk2 project to the
edk2-libc project, in commit 964f432b9b ("edk2: Remove AppPkg, StdLib,
StdLibPrivateInternalFiles", 2019-04-29).

We'd like to use the inet_pton() function in CryptoPkg. Resurrect the
"inet_pton.c" file from just before the StdLib removal, as follows:

  $ git show \
      964f432b9b0a^:StdLib/BsdSocketLib/inet_pton.c \
      > CryptoPkg/Library/BaseCryptLib/SysCall/inet_pton.c

The inet_pton() function is only intended for the DXE phase at this time,
therefore only the "BaseCryptLib" instance INF file receives the new file.

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiaxin Wu <jiaxin.wu@intel.com>
Cc: Sivaraman Nainar <sivaramann@amiindia.co.in>
Cc: Xiaoyu Lu <xiaoyux.lu@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=960
CVE: CVE-2019-14553
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>

CryptoPkg/Library/Include/CrtLibSupport.h

@@ -192,6 +192,7 @@ void           abort       (void) __attribute__((__noreturn__));
 #else
 void           abort       (void);
 #endif
+int            inet_pton   (int, const char *, void *);
 
 //
 // Macros that directly map functions to BaseLib, BaseMemoryLib, and DebugLib functions