build: Remove backup Makefile targets.

These commands are a relic of a non-distributed VCS. Now, if you need to
backup your work, just make a commit. No-one else has to see it, but
it's a lot safer that way. And if you don't want to go through the
trouble of a commit, just run `git stash` instead.

Makefile.in

@@ -51,7 +51,7 @@ AR = ar
 ARFLAGS = cru
 RANLIB = ranlib
 
-##.PHONY: clean default all backup bak generate_databases specfem3D meshfem3D
+##.PHONY: clean default all generate_databases specfem3D meshfem3D
 
 ####
 #### targets
@@ -80,11 +80,6 @@ all: default \
 
 required: bin lib obj
 
-backup:
-	cp -rp src DATA Makefile go_generate_databases* go_mesher* go_solver* mymachines bak
-
-bak: backup
-
 mesh : meshfem3D
 gen : generate_databases
 spec : specfem3D

src/generate_databases/Makefile.in

@@ -181,11 +181,6 @@ default: $(DEFAULT)
 
 all: clean default
 
-backup:
-	cp *f90 *h README_SPECFEM3D DATA/Par_file* Makefile go_generate_databases* go_mesher* go_solver* mymachines bak
-
-bak: backup
-
 generate_databases: xgenerate_databases