Finish adding mmake variables for C#.

About a week ago, Julien added targets to */Mmakefile to build .cs files.
These referred to undefined mmake variables of the form "program_name.css".

compiler/write_deps_file.m:
    Add rules to generate definitions for "program_name.css".
    Following the pattern of similar definitions such as program_name.javas,
    these refer to other mmake variables css_subdir and cs_date_subdir.

scripts/Mmake.vars.in:
    Add definitions for css_subdir and cs_date_subdir.

compiler/write_deps_file.m

@@ -1259,6 +1259,11 @@ generate_dv_file(Globals, SourceFileName, ModuleName, DepsMap,
             [s(ModuleMakeVarName)])]),
     add_mmake_entry(MmakeVarClasses, !MmakeFile),
 
+    MmakeVarCss = mmake_var_defn(ModuleMakeVarName ++ ".css",
+        string.format("$(%s.mods:%%=$(css_subdir)%%.cs)",
+            [s(ModuleMakeVarName)])),
+    add_mmake_entry(MmakeVarCss, !MmakeFile),
+
     MmakeVarDirs = mmake_var_defn(ModuleMakeVarName ++ ".dirs",
         string.format("$(%s.mods:%%=$(dirs_subdir)%%.dir)",
             [s(ModuleMakeVarName)])),
@@ -1306,6 +1311,11 @@ generate_dv_file(Globals, SourceFileName, ModuleName, DepsMap,
             [s(ModuleMakeVarName)])),
     add_mmake_entry(MmakeVarJavaDates, !MmakeFile),
 
+    MmakeVarCsDates = mmake_var_defn(ModuleMakeVarName ++ ".cs_dates",
+        string.format("$(%s.mods:%%=$(cs_dates_subdir)%%.cs_date)",
+            [s(ModuleMakeVarName)])),
+    add_mmake_entry(MmakeVarCsDates, !MmakeFile),
+
     MmakeVarDs = mmake_var_defn(ModuleMakeVarName ++ ".ds",
         string.format("$(%s.mods:%%=$(ds_subdir)%%.d)",
             [s(ModuleMakeVarName)])),

scripts/Mmake.vars.in

@@ -526,12 +526,14 @@ cs_subdir=$(SUBDIR)cs/
 dlls_subdir=$(SUBDIR)dlls/
 os_subdir=$(SUBDIR)os/
 javas_subdir=$(SUBDIR)javas/
+css_subdir=$(SUBDIR)css/
 dirs_subdir=$(SUBDIR)dirs/
 c_dates_subdir=$(SUBDIR)c_dates/
 s_dates_subdir=$(SUBDIR)s_dates/
 pic_s_dates_subdir=$(SUBDIR)pic_s_dates/
 java_dates_subdir=$(SUBDIR)java_dates/
 classes_subdir=$(SUBDIR)classs/
+cs_dates_subdir=$(SUBDIR)cs_dates/
 err_dates_subdir=$(SUBDIR)err_dates/
 
 else
@@ -560,12 +562,14 @@ cs_subdir=
 dlls_subdir=
 os_subdir=
 javas_subdir=
+css_subdir=
 dirs_subdir=
 c_dates_subdir=
 s_dates_subdir=
 pic_s_dates_subdir=
 java_dates_subdir=
 classes_subdir=
+cs_dates_subdir=
 err_dates_subdir=
 
 endif