[LLVM] Do not require shell for some tests (#94595)

Remove `REQUIRES: shell` from some tests that seem fine without it.
Tested on Windows and with LIT_USE_INTERNAL_SHELL=1 on Linux.

Author: jayfoad

llvm/test/DebugInfo/symbolize-gnu-debuglink-no-realpath.test

@@ -1,4 +1,3 @@
-# REQUIRES: shell
 # Ensure that no realpath assumptions are made about .gnu_debuglink paths.
 
 # Copy inputs to some other location with arbitrary names, with the original

llvm/test/Other/can-execute.txt

@@ -1,5 +1,4 @@
 REQUIRES: can-execute
-REQUIRES: shell
 
 This tests that we abstract two peculiarities of unix in can_execute:
 

llvm/test/Other/lit-unicode.txt

@@ -1,5 +1,4 @@
 FIXME: See if we can fix this in lit by using Unicode strings.
-REQUIRES: shell
 
 RUN: echo "ようこそ" | FileCheck %s
 CHECK: {{^}}ようこそ{{$}}

llvm/test/tools/llvm-cov/gcov/intermediate-format.test

@@ -1,5 +1,3 @@
-REQUIRES: shell
-
 RUN: rm -rf %t && mkdir %t && cd %t
 RUN: cp %S/Inputs/test.gcno %S/Inputs/test.gcda .
 

llvm/test/tools/llvm-rc/windres-prefix.test

@@ -1,5 +1,3 @@
-; REQUIRES: shell
-
 ; RUN: rm -rf %t && mkdir %t
 
 ; Check that a triple prefix on the executable gets picked up as target triple.

llvm/test/tools/split-file/output-is-special.test

@@ -1,5 +1,4 @@
 # UNSUPPORTED: system-windows
-# REQUIRES: shell
 
 ## Don't delete the output if it is special, otherwise root may accidentally
 ## remove important special files.