remove all uses of condsyms symbols defined prior to bootstrap nim 0.20.0 (#16918)

* nimNoArrayToCstringConversion deadcode
* nimbabel deadcode
* nimHasalignOf deadcode
* nimvarargstyped deadcode
* nimhygiene deadcode
* nimNewTypedesc deadcode
* nimlocks deadcode
* nimHasCppDefine deadcode
* nimHasRunnableExamples deadcode
* nimHasNilChecks deadcode
* nimSymKind deadcode
* minor macros refactoring
* nimVmEqIdent deadcode
* nimNoNil deadcode
* nimNoZeroTerminator deadcode
* nimHasSymOwnerInMacro deadcode
* nimVmExportFixed deadcode
* nimNewRuntime deadcode
* nimAshr deadcode
* nimUncheckedArrayTyp deadcode
* nimHasTypeof deadcode
* nimErrorProcCanHaveBody deadcode
* nimHasHotCodeReloading deadcode
* nimHasSignatureHashInMacro deadcode
* nimHasDefault deadcode
* nimMacrosSizealignof deadcode

config/config.nims

@@ -1,5 +1,4 @@
 # this config.nims also needs to exist to prevent future regressions, see #9990
 
-when defined(nimHasCppDefine):
-  cppDefine "errno"
-  cppDefine "unix"
+cppDefine "errno"
+cppDefine "unix"

config/nim.cfg

@@ -43,14 +43,12 @@ path="$lib/arch"
 path="$lib/core"
 path="$lib/pure"
 
-@if nimbabel:
-  @if not windows:
-    nimblepath="/opt/nimble/pkgs/"
-  @else:
-    # TODO:
-  @end
-  nimblepath="$home/.nimble/pkgs/"
+@if not windows:
+  nimblepath="/opt/nimble/pkgs/"
+@else:
+  # TODO:
 @end
+nimblepath="$home/.nimble/pkgs/"
 
 @if danger or quick:
   obj_checks:off
@@ -64,9 +62,7 @@ path="$lib/pure"
   debugger:off
   line_dir:off
   dead_code_elim:on
-  @if nimHasNilChecks:
-    nilchecks:off
-  @end
+  nilchecks:off
 @end
 
 @if release or danger: