Align Kconfig and Kbuild logic to Linux 4.18 release with minimal impact
on files outside of this scope.

Our previous Kconfig sync was done by commit e91610da

 ("kconfig:
re-sync with Linux 4.17-rc4").

A very small number of changes upstream since our sync with v4.17-rc4
that exist in the v4.18 release have already been applied here and have
been omitted from the list in this commit (and are readily available in
our own git history).

The imported Linux commits are:
[From prior to v4.17-rc4]
39a33ff80a25 kbuild: remove cc-option-align
db547ef19064 Kbuild: don't add obj tree in additional includes
b999596b963a Kbuild: don't add ../../ to include path

[From v4.17 to v4.18]
b3aa58d2e85d fixdep: suppress consecutive / from file paths in dependency list files
74656b682902 kbuild: disable new dtc graph and unit-address warnings
74d931716151 genksyms: remove symbol prefix support
e6ecfb45072c kbuild: do not display CHK for filechk
0b669a5076fd kconfig: refactor Qt package checks for building qconf
b464ef583dc7 kconfig: refactor GTK+ package checks for building gconf
1c5af5cf9308 kconfig: refactor ncurses package checks for building mconf and nconf
694c49a7c01c kconfig: drop localization support
96f60dfa5819 trace: Use -mcount-record for dynamic ftrace
bb222ceeb327 kconfig: remove string expansion in file_lookup()
96d8e48da55a kconfig: remove string expansion for mainmenu after yyparse()
5b31a9746756 kconfig: remove sym_expand_string_value()
137c0118a900 kconfig: make default prompt of mainmenu less specific
e298f3b49def kconfig: add built-in function support
2fd5b09c201e kconfig: add 'shell' built-in function
9de071536c87 kconfig: begin PARAM state only when seeing a command keyword
9ced3bddec08 kconfig: support user-defined function and recursively expanded variable
1175c02506ff kconfig: support simply expanded variable
ed2a22f277c6 kconfig: support append assignment operator
82bc8bd82e5c kconfig: expand lefthand side of assignment statement
1d6272e6fe43 kconfig: add 'info', 'warning-if', and 'error-if' built-in functions
a702a6176e2f kconfig: add 'filename' and 'lineno' built-in variables
915f64901eb3 kconfig: error out if a recursive variable references itself
2bece88f89fa kconfig: test: add Kconfig macro language tests
21c54b774744 kconfig: show compiler version text in the top comment
59f7b5847b0c kbuild: $(CHECK) doesnt need NOSTDINC_FLAGS twice
145167650b96 kbuild: add endianness flag to CHEKCFLAGS
1f2f01b122d7 kbuild: add machine size to CHECKFLAGS
d6a0c8a1326b kconfig: Add testconfig into make help output
bb6d83dde191 kbuild: Move last word of nconfig help to the previous line
8593080c0fcf kconfig: fix localmodconfig
ed7d40bc67b8 tracing: Fix SKIP_STACK_VALIDATION=1 build due to bad merge with -mrecord-mcount
b2d00d7c61c8 kconfig: fix line numbers for if-entries in menu tree
ecd53ac2f2c6 kconfig: handle P_SYMBOL in print_symbol()
73d1c580f92b kconfig: loop boundary condition fix
48f6e3cf5bc6 kbuild: do not drop -I without parameter
bd412d81b7ea kbuild: .PHONY is not a variable, but PHONY is
6916162c7308 kbuild: remove duplicated comments about PHONY

Cc: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>