[docs] Fixed incorrect build instructions for Scudo

[cryptoad]

Summary

The docs previously said to compile *.cc, but the C++ files in that directory all use the .cpp extension.

[alex]

FYI, I'm not an LLVM committer, so I'll need someone to merge this for me. Thanks!

[cryptoad]

In D70860#1764188, @alex wrote:

FYI, I'm not an LLVM committer, so I'll need someone to merge this for me. Thanks!

Ack, I'll get to it shortly.
I have to redo the whole thing since it's not accounting for the new "standalone" version of the allocator.

[alex]

FWIW, another thing that probably deserves to be mentioned is that compiling it this way does not get you the GWP-ASAN integration, you need to go via CMake if you want that.

[cryptoad]

Docs have been udpated some time ago with new build instructions to reflect the migration to the standalone version. Abandoning this.

[alex]

LGTM

llvm/docs/ScudoHardenedAllocator.rst

 functions.
 
 You may also build Scudo like this: 
 
 .. code:: console
 
   cd $LLVM/projects/compiler-rt/lib
   clang++ -fPIC -std=c++11 -msse4.2 -O2 -I. scudo/*.cpp \
-    $(\ls sanitizer_common/*.{cc,S} | grep -v "sanitizer_termination\|sanitizer_common_nolibc\|sancov_\|sanitizer_unwind\|sanitizer_symbol") \
+    $(\ls sanitizer_common/*.{cpp,S} | grep -v "sanitizer_termination\|sanitizer_common_nolibc\|sancov_\|sanitizer_unwind\|sanitizer_symbol") \
     -shared -o libscudo.so -pthread
 
 and then use it with existing binaries as follows:
 
 .. code:: console
 
   LD_PRELOAD=`pwd`/libscudo.so ./a.out