build: configure doesn't pickup Qt if depends is built with DEBUG=1 #16391

Using master (536590f358dc3d3e5821eba7f1009452ea93b205) and building depends using DEBUG=1 make -j8.

Configuring with ./autogen.sh && ./configure --prefix=/Users/michael/github/bitcoin/depends/x86_64-apple-darwin18.6.0 I'm seeing:

Options used to compile and link:
  with wallet   = yes
  with gui / qt = no
  with zmq      = yes
  with test     = yes
    with fuzz   = no
  with bench    = yes
  with upnp     = yes
  use asm       = yes
  sanitizers    = 
  debug enabled = no
  gprof enabled = no
  werror        = no

  target os     = darwin
  build os      = darwin

In config.log:

configure:27984: checking for static Qt plugins: -lqcocoa
ld: library not found for -lqcocoa
configure:27813: checking for static Qt plugins: -lqminimal
ld: library not found for -lqminimal
configure:27839: WARNING: Could not resolve: -lqminimal; bitcoin-qt frontend will not be built

Building depends without DEBUG=1 works as expected.

Tested on current master (646f0ada0205ae4b3952107e3b1542f06adda32b).

Can confirm such behavior on macOS 10.14:

$ clang --version | head -2
Apple LLVM version 10.0.1 (clang-1001.0.46.4)
Target: x86_64-apple-darwin18.0.0

Native build with depends works fine on Linux Mint 19.3:

$ gcc --version | head -1
gcc (Ubuntu 7.4.0-1ubuntu1~18.04.1) 7.4.0

It seems this issue is macOS-target specific.

UPDATE:

$ DEBUG=1 make HOST=x86_64-apple-darwin16 -C depends
$ CONFIG_SITE=$PWD/depends/x86_64-apple-darwin16/share/config.site ./configure 

also causes an error on Linux with GCC 7.4

@fanquake Mind looking into #18298?

I can reproduce this is issue on macOS 10.15.5 (master: 265492723a6874abc542361e4693840240e7d2ef), will try @hebasto's PR.