tests/make: force expected lines to be listed in execution order

The diagnostics from the program to check the "expect" lines in the unit
test files were hard to follow since the "out-of-order" lines were
confusing. For out-of-order lines, state where they should be placed
instead.

make: add program name to stack traces from sub-makes

make: add quotes to "in directory" line in stack traces

The other lines in stack traces use quotes as well.

make: use '"filename" line 123' for locations instead of 'filename:123'

The format 'filename:123' is commonly used for identifying a location in
a file. Text editors recognize it and allow quick navigation through it.
The previous format was specific to make and would have required custom
support in editors.

The new format was already used in stack traces, except for the first
line. Now all lines use the same format.

make: reduce line length in error messages

The error messages for deeply nested parse errors were hard to decipher,
due to the large amount of text. Split these messages into individual
lines, just as in the backtrace for .include files and .for loops. This
unified backtrace makes the output more uniform.

make: on error, print the targets to be made

This helps to understand situations with several nested sub-makes in
varying directories.

make: add more context information to error messages

In case of a parse error or evaluation error, print the variable value
in addition to the variable name, to see the effects of previous
expression modifiers.

In nested make calls, print the current directory at the bottom of a
stack trace, as that information is otherwise hard to get in a parallel
build spanning multiple directories.

make: error out on syntax error in conditions in ':?then:else' modifier

The 'Error' function only reports errors but does not affect the exit
status, the 'Parse_Error' function does, while providing more details to
find the cause of the syntax error.

branches: 1.5.2;
make: remove redundant text from diagnostic about bad '?:' modifier

make: use straight quotes for error 'Bad conditional expression'

This diagnostic was supposed to be an error, see ApplyModifier_IfElse.

When such an error occurs while the makefiles are read, make stops with
an error, as can be expected. But when such an error occurs later,
after all makefiles have been read, the message is printed but make does
not stop.

In lint mode (-dL), make stops in such a case. I didn't dare to make
this the default behavior, out of fear of breaking existing build
infrastructure, not only in NetBSD or pkgsrc, but also FreeBSD and other
operating systems that use the bmake distribution, generated from the
same source code.

make(1): add test for undefined (or empty) variable in :? modifier

usr.bin/make: fix test for late evaluated condition

usr.bin/make: add test case for lazy conditions