Falco does not compile against glibc 2.30

[fntlnz]

What would you like to be added:

Falco can't compile against glibc 2.30 because this version has a function called gettid which is also declared in our other dependency gRPC 1.8.1

In gRPC the issue was fixed by this PR grpc/grpc#18950

src/core/lib/support/log_linux.cc:42:13: error: ambiguating new declaration of 'long int gettid()'                                                                                                                                                                      
   42 | static long gettid(void) { return syscall(__NR_gettid); }                                                                                                                                                                                                       
      |             ^~~~~~                                                                                                                                                                                                                                              
In file included from /usr/include/unistd.h:1170,                                                                                                                                                                                                                       
                 from src/core/lib/support/log_linux.cc:40:                                                                                                                                                                                                             
/usr/include/bits/unistd_ext.h:34:16: note: old declaration '__pid_t gettid()'                                                                                                                                                                                          
   34 | extern __pid_t gettid (void) __THROW;                                                                                                                                                                                                                           
      |                ^~~~~~                                                                                                                                                                                                                                           
src/core/lib/support/log_linux.cc:42:13: error: 'long int gettid()' defined but not used [-Werror=unused-function]                                                                                                                                                      
   42 | static long gettid(void) { return syscall(__NR_gettid); }                                                                                                                                                                                                       
      |             ^~~~~~                                                                                                                                                                                                                                              
cc1plus: all warnings being treated as errors                                                                                                                                                                                                                           
make[3]: *** [Makefile:2587: /home/fntlnz/Projects/falcosecurity/falco/build/grpc-prefix/src/grpc/objs/opt/src/core/lib/support/log_linux.o] Error 1                                                                                                                    
make[2]: *** [CMakeFiles/grpc.dir/build.make:118: grpc-prefix/src/grpc-stamp/grpc-build] Error 2                                                                                                                                                                        
make[1]: *** [CMakeFiles/Makefile2:391: CMakeFiles/grpc.dir/all] Error 2                                                                                                                                                                                                
make: *** [Makefile:152: all] Error 2   

Why is this needed:

Because we want people to be able to compile falco when they update glibc and gcc.

[prankkelkar]

I am facing this issue on ubuntu 19.10.
root@prasanna:/home/ubuntu/0.18.0/falco/build/release# ldd --version ldd (Ubuntu GLIBC 2.30-0ubuntu2) 2.30 Copyright (C) 2019 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Written by Roland McGrath and Ulrich Drepper.
How are we planning to overcome this ?

[fntlnz]

@prankkelkar We need to update the gRPC library in order to do this but we need to write some key features test first to ensure we don't break anything. In the meanwhile I'm restructuring how we use gRPC as a dependency to make the update work faster and smoother once we can update.