dim: Replace git commit --amend from dim_apply with dimrc option

Introduce DIM_POST_APPLY_ACTION to dimrc that allows the user to specify
a command to be run after a patch is applied. Use eval so enviroment
variables can be overriden with the option. For example:

DIM_POST_APPLY_ACTION="EDITOR=\"gedit -w\" git commit --amend"

v2: Initialize variable with default value.
    Fix dimrc.sample to match default value.

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

dim

@@ -65,6 +65,9 @@ DIM_DRM_UPSTREAM_REMOTE=${DIM_DRM_UPSTREAM_REMOTE:-airlied}
 # usage: $DIM_MUA [-s subject] [-i file] [-c cc-addr] to-addr [...]
 DIM_MUA=${DIM_MUA:-mutt}
 
+# command to run after dim apply
+DIM_POST_APPLY_ACTION=${DIM_POST_APPLY_ACTION:-}
+
 # greetings pull request template
 DIM_TEMPLATE_HELLO=${DIM_TEMPLATE_HELLO:-$HOME/.dim.template.hello}
 
@@ -383,7 +386,7 @@ function dim_apply
 		commit_add_tag "Link" "http://patchwork.freedesktop.org/patch/msgid/$message_id"
 	fi
 
-	git commit --amend &
+	eval $DRY $DIM_POST_APPLY_ACTION
 }
 
 function magic_patch

dimrc.sample

@@ -21,3 +21,6 @@
 # Mail User Agent supporting a subset of mutt(1) command line options:
 # [-s subject] [-i file] [-c cc-addr] to-addr [...]
 #DIM_MUA=mutt
+
+# Command to run after dim apply
+#DIM_POST_APPLY_ACTION=