Support configure with --extra-ldflags. v5.0.199 v6.0.99 #2984

Job	Run time
multiple-arch-armv7	5m 56s
multiple-arch-aarch64	5m 38s
cygwin64-cache	2m 45s
utest-regression-blackbox-test	4m 59s
cygwin64	12m 29s
fast	1s
build-centos7	2m 19s
build-cross-aarch64	2m 22s
build-cross-arm	2m 18s
build-ubuntu16	1m 42s
build-ubuntu18	2m 41s
build-ubuntu20	2m 31s
coverage	2m 36s
multiple-arch-amd64	1m 16s
test-done	1s
	49m 34s

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