tweak the error printed for PrecompileError to indicate that it doe…

…sn't have to be due to `__precompile__(false)` (JuliaLang#51367)

base/loading.jl

@@ -1747,7 +1747,7 @@ end
 # we throw PrecompilableError when a module doesn't want to be precompiled
 struct PrecompilableError <: Exception end
 function show(io::IO, ex::PrecompilableError)
- print(io, "Declaring __precompile__(false) is not allowed in files that are being precompiled.")
+ print(io, "Error when precompiling module, potentially caused by a __precompile__(false) declaration in the module.")
 end
 precompilableerror(ex::PrecompilableError) = true
 precompilableerror(ex::WrappedException) = precompilableerror(ex.error)