$ CONFIG_SITE=$PWD/depends/x86_64-pc-linux-gnu/share/config.site ./configure
...
  CC            = gcc -m64
  CFLAGS        = -pipe -O2
  CPPFLAGS      =   -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -I/home/hebasto/bitcoin/depends/x86_64-pc-linux-gnu/share/../include/  -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS
  CXX           = g++ -m64 -std=c++11
  CXXFLAGS      =   -fstack-reuse=none -Wstack-protector -fstack-protector-all     -pipe -O2
  LDFLAGS       = -pthread  -Wl,-z,relro -Wl,-z,now -pie  -L/home/hebasto/bitcoin/depends/x86_64-pc-linux-gnu/share/../lib
  ARFLAGS       = cr

$ ./configure
...
  CC            = gcc
  CFLAGS        = -g -O2
  CPPFLAGS      =   -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2  -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS
  CXX           = g++ -std=c++11
  CXXFLAGS      =   -fstack-reuse=none -Wstack-protector -fstack-protector-all  -Wall -Wextra -Wformat -Wvla -Wswitch -Wformat-security -Wredundant-decls -Wunused-variable -Wdate-time  -Wno-unused-parameter -Wno-implicit-fallthrough   -g -O2
  LDFLAGS       = -pthread  -Wl,-z,relro -Wl,-z,now -pie
  ARFLAGS       = cr