Mass rename Ebb and relatives to Block (#1365)

* Manually rename BasicBlock to BlockPredecessor

BasicBlock is a pair of (Ebb, Inst) that is used to represent the
basic block subcomponent of an Ebb that is a predecessor to an Ebb.

Eventually we will be able to remove this struct, but for now it
makes sense to give it a non-conflicting name so that we can start
to transition Ebb to represent a basic block.

I have not updated any comments that refer to BasicBlock, as
eventually we will remove BlockPredecessor and replace with Block,
which is a basic block, so the comments will become correct.

* Manually rename SSABuilder block types to avoid conflict

SSABuilder has its own Block and BlockData types. These along with
associated identifier will cause conflicts in a later commit, so
they are renamed to be more verbose here.

* Automatically rename 'Ebb' to 'Block' in *.rs

* Automatically rename 'EBB' to 'block' in *.rs

* Automatically rename 'ebb' to 'block' in *.rs

* Automatically rename 'extended basic block' to 'basic block' in *.rs

* Automatically rename 'an basic block' to 'a basic block' in *.rs

* Manually update comment for `Block`

`Block`'s wikipedia article required an update.

* Automatically rename 'an `Block`' to 'a `Block`' in *.rs

* Automatically rename 'extended_basic_block' to 'basic_block' in *.rs

* Automatically rename 'ebb' to 'block' in *.clif

* Manually rename clif constant that contains 'ebb' as substring to avoid conflict

* Automatically rename filecheck uses of 'EBB' to 'BB'

'regex: EBB' -> 'regex: BB'
'$EBB' -> '$BB'

* Automatically rename 'EBB' 'Ebb' to 'block' in *.clif

* Automatically rename 'an block' to 'a block' in *.clif

* Fix broken testcase when function name length increases

Test function names are limited to 16 characters. This causes
the new longer name to be truncated and fail a filecheck test. An
outdated comment was also fixed.

cranelift/filetests/filetests/regalloc/infinite-interference.clif

@@ -7,31 +7,31 @@ target riscv32
 ; resolve that conflict since v1 will just interfere with the inserted copy too.
 
 ;function %c1(i32) -> i32 {
-;ebb0(v0: i32):
+;block0(v0: i32):
 ;    v1 = iadd_imm v0, 1
 ;    v2 = iconst.i32 1
-;    brz v1, ebb1(v2)
-;    jump ebb2
+;    brz v1, block1(v2)
+;    jump block2
 ;
-;ebb1(v3: i32):
+;block1(v3: i32):
 ;    return v3
 ;
-;ebb2:
-;    jump ebb1(v1)
+;block2:
+;    jump block1(v1)
 ;}
 
 ; Same thing with v1 and v2 swapped to reverse the order of definitions.
 
 function %c2(i32) -> i32 {
-ebb0(v0: i32):
+block0(v0: i32):
     v1 = iadd_imm v0, 1
     v2 = iconst.i32 1
-    brz v2, ebb1(v1)
-    jump ebb2
+    brz v2, block1(v1)
+    jump block2
 
-ebb1(v3: i32):
+block1(v3: i32):
     return v3
 
-ebb2:
-    jump ebb1(v2)
+block2:
+    jump block1(v2)
 }