Pre-generate gen_table.c

This removes a build-time dependency on the py34-enum PyPI package. It
shouldn’t be necessary to install that package just to build the C/C++
libraries.

Makefile

@@ -38,7 +38,9 @@ test-vim:
 
 .PHONY: regen
 regen:
-	src/c/scripts/gen.py --python=src/python/procyon/spec.py
+	src/c/scripts/gen.py \
+		--c=src/c/src/gen_table.c \
+		--python=src/python/procyon/spec.py
 
 .PHONY: clean
 clean:

src/c/BUILD.gn

@@ -14,7 +14,6 @@
 
 static_library("procyon") {
   sources = [
-    "$target_gen_dir/gen_table.c",
     "include/procyon.h",
     "src/common.c",
     "src/common.h",
@@ -23,6 +22,7 @@ static_library("procyon") {
     "src/error.c",
     "src/file.c",
     "src/format.c",
+    "src/gen_table.c",
     "src/gen_table.h",
     "src/io.c",
     "src/lex.c",
@@ -43,27 +43,10 @@ static_library("procyon") {
     sources += [ "src/file_linux.c" ]
   }
 
-  deps = [
-    ":gen_from_spec",
-  ]
-
   public_configs = [ ":procyon_public" ]
   configs += [ ":procyon_private" ]
 }
 
-action("gen_from_spec") {
-  script = "scripts/gen.py"
-  gen_table = "$target_gen_dir/gen_table.c"
-
-  args = [ "--c=" + rebase_path(gen_table, root_build_dir) ]
-  inputs = [
-    "src/spec.pn",
-  ]
-  outputs = [
-    gen_table,
-  ]
-}
-
 config("procyon_public") {
   include_dirs = [ "include" ]
   libs = [ "-lm" ]