CMake fixes

[Ninja3047]

• move doctest to cxx-common: add doctest, used in a number of projects cxx-common#964 and remove submodule from repo
• update git_watcher.cmake to fix some bugs, most notably changing CMAKE_BINARY_DIR to CMAKE_CURRENT_BINARY_DIR
• remove llvm.cmake and janky find_llvm, use upstream llvm recommended cmake incantation
• update FindZ3.cmake to fix some bugs, most notably changing CMAKE_SOURCE_DIR a temporary path

[Ninja3047]

won't build until lifting-bits/cxx-common#964 gets merged and tagged so do not merge until then

[github-actions]

See the diff generated by this PR for the tests here: https://github.com/lifting-bits/rellic/actions/runs/2950063358

fizzbuzz.bc

typedefs_of_typedefs.bc

switch_loop.bc

func_cond_zero_arg.bc

fcmp.bc

conflicting_names.bc

struct.bc

issue_183_literal_structs.bc

zeroinit.bc

issue_127_uint128_t_lit.bc

struct_swap.bc

init_list.bc

ret0.bc

bool.bc

short.bc

cast.bc

nullptr.bc

nested_struct.bc

array_swap.bc

binops.bc

bitmask.bc

loop.bc

float.bc

reg_test_structure_fields.bc

vectors.bc

funcptr.bc

goto_loop.bc

branch.bc

bitops.bc

trunc.bc

inttoptr.bc

issue_4.bc

issue_123_uint128_t.bc

fizzbuzz_stateful.bc

issue_94_strncmp.bc

global_using_function_decl.bc

byval_struct.bc

nested_while.bc

--- /dev/fd/63	2022-08-29 16:33:47.666364756 +0000
+++ /dev/fd/62	2022-08-29 16:33:47.666364756 +0000
@@ -18,14 +18,14 @@
                 printf("loop1 x: %d\n", var1);
             }
     }
-    if ((int)var1 >= 20 || (int)var1 <= 10) {
+    if ((int)var1 <= 10 || (int)var1 >= 20) {
         while ((int)var1 < 20)
             {
                 var1 = var1 + 1U;
                 printf("loop2 x: %d\n", var1);
             }
     }
-    if (((int)var1 >= 20 || (int)var1 <= 10) && (int)var1 >= 20) {
+    if (((int)var1 <= 10 || (int)var1 >= 20) && (int)var1 >= 20) {
         return var0;
     }
 }

func_cond_two_arg.bc

conflicting_global.bc

assert.bc

zext.bc

switch.bc

template_parameter_pack.bc

byval_tail_nogep.ll

byval_tail_gep.ll

[ekilmer]

LGTM! Thank you for the cleanup!