rename from build/.gdbinit
rename to .gdbinit

--- a/build/Makefile.in
+++ b/build/Makefile.in
@@ -94,17 +94,18 @@ endif
 ifdef MOZ_EXTENSION_MANAGER
 DEFINES += -DMOZ_EXTENSION_MANAGER
 endif
 
 endif
 
 # Put a useful .gdbinit in the bin directory, to be picked up automatically
 # by GDB when we debug executables there.
-GDBINIT_FILES := .gdbinit
+# NOTE: Keep .gdbinit in the topsrcdir for people who run gdb from the topsrcdir.
+GDBINIT_FILES := $(topsrcdir)/.gdbinit
 GDBINIT_DEST = $(FINAL_TARGET)
 INSTALL_TARGETS += GDBINIT
 
 PYTHON_UNIT_TESTS := \
   tests/unit-ConfigStatus.py \
   tests/test.py \
   $(NULL)