Change in flashrom[master]: Makefile: Make pkg-config mandatory to find libusb1

[Thomas Heijligen (Code Review)]

Attention is currently required from: Nico Huber, Thomas Heijligen.
Hello build bot (Jenkins), Nico Huber, Angel Pons,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/flashrom/+/59049

to look at the new patch set (#10).

Change subject: Makefile: Make pkg-config mandatory to find libusb1
......................................................................

Makefile: Make pkg-config mandatory to find libusb1

Use `make HAS_LIBUSB1=yes/no` to override the pkg-config detection and
`CONFIG_LIBUSB1_CFLAGS` and `CONFIG_LIBUSB1_LDFLAGS` to set cflags and
ldflags manually.

Change-Id: I4f24be647d25dde24c41514f8964b7134205867c
Signed-off-by: Thomas Heijligen 
---
M Makefile
M Makefile.include
2 files changed, 19 insertions(+), 56 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/49/59049/10