[clang-tidy] Optimize GlobList::contains

With large lists of checks and large number of warnings GlobList::contains
starts being ridiculously CPU hungry, since it runs regexp match per glob.
Caching results of glob matching in a StringMap significantly speeds up check
filtering even for small GlobLists.

/tmp/q.cc:

void f() {
  int I;
  {int I;}
  {int I;}
  {int I;}
  ... // 200k times
}

Before the patch:

GlobList with 2 entries:
  $ time clang-tidy-old -checks=-*,modernize-use-override /tmp/q.cc -- -Wshadow
  200000 warnings generated.
  Suppressed 200000 warnings (200000 with check filters).

  real    0m3.826s
  user    0m3.176s
  sys     0m0.504s

GlobList with 28 entries:
  $ time clang-tidy-old -checks=-*,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,modernize-use-override /tmp/q.cc -- -Wshadow
  200000 warnings generated.
  Suppressed 200000 warnings (200000 with check filters).

  real    0m5.000s
  user    0m4.744s
  sys     0m0.060s

GlobList with 158 entries:
  $ time clang-tidy-old -checks=-*,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,modernize-use-override /tmp/q.cc -- -Wshadow
  200000 warnings generated.
  Suppressed 200000 warnings (200000 with check filters).

  real    0m13.920s
  user    0m13.636s
  sys     0m0.104s

With the patch runtime is practically independent from the length of the GlobList:
  $ time clang-tidy-new -checks=-*,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,modernize-use-override /tmp/q.cc -- -Wshadow
  200000 warnings generated.
  Suppressed 200000 warnings (200000 with check filters).

  real    0m2.300s
  user    0m2.104s
  sys     0m0.044s

llvm-svn: 303321