Update tests to use FileCheck instead of grep (which is deprecated in the LLVM regression suite)

test/Transforms/NaCl/expand-tls.ll

 ; RUN: opt < %s -nacl-expand-tls -S | FileCheck %s
 
 ; All thread-local variables should be removed
-; RUN: opt < %s -nacl-expand-tls -S | not grep thread_local
+; RUN: opt < %s -nacl-expand-tls -S | FileCheck %s -check-prefix=NO_TLS
 
+; NO_TLS-NOT: thread_local
 
 @tvar1 = thread_local global i64 123
 @tvar2 = thread_local global i32 456
 
 
 ; CHECK: %tls_init_template = type <{ i64, i32 }>
 ; CHECK: %tls_struct = type <{ %tls_init_template, %tls_bss_template }>
 ; CHECK: %tls_bss_template = type <{ [4 x i8] }>
 
 
@@ skipping 50 matching lines @@
 declare i32 @llvm.nacl.tp.tls.offset(i32)
 declare i32 @llvm.nacl.tp.tdb.offset(i32)
 
 define i32 @test_get_tp_tls_offset(i32 %tls_size) {
   %offset = call i32 @llvm.nacl.tp.tls.offset(i32 %tls_size)
   ret i32 %offset
 }
 ; Uses of the intrinsic are replaced with uses of a regular function.
 ; CHECK: define i32 @test_get_tp_tls_offset
 ; CHECK: call i32 @nacl_tp_tls_offset
-; RUN: opt < %s -nacl-expand-tls -S | not grep llvm.nacl.tp.tls.offset
+; NO_TLS-NOT: llvm.nacl.tp.tls.offset
 
 define i32 @test_get_tp_tdb_offset(i32 %tdb_size) {
   %offset = call i32 @llvm.nacl.tp.tdb.offset(i32 %tdb_size)
   ret i32 %offset
 }
 ; Uses of the intrinsic are replaced with uses of a regular function.
 ; CHECK: define i32 @test_get_tp_tdb_offset
 ; CHECK: call i32 @nacl_tp_tdb_offset
-; RUN: opt < %s -nacl-expand-tls -S | not grep llvm.nacl.tp.tdb.offset
+; NO_TLS-NOT: llvm.nacl.tp.tdb.offset