fix compilation on Debian 7 (no git -C) (#18427)

* fix compilation on Debian 7 (no git -C)

* address review

* allow specify branch for testing unmerged csources

* temporarily change csources checkout parameters for testing

* Update tools/deps.nim

Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>

* fix failure

* Update config/build_config.txt

* set proper git branch/hash

Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>

tools/niminst/makefile.nimf

@@ -25,7 +25,8 @@ endif
 
 ifeq ($(uos),linux)
   myos = linux
-  LDFLAGS += -ldl -lm
+  # add -lrt to avoid "undefined reference to `clock_gettime'" with glibc<2.17
+  LDFLAGS += -ldl -lm -lrt
 endif
 ifeq ($(uos),dragonfly)
   myos = freebsd