Optimize Bazel external dependencies

This change does the following:

- Always use {,new_}http_archive rather than git_repository
- Make liberal use of strip_prefix
- Clarify licenses() in BUILD files
- On POSIX include headers like a normal C/C++ program

This change accomplishes the following:

- Reduce download size >100MB: The biggest culprit is grpc which has
  tens of thousands of commits in its GitHub repository.

- Reduce disk size >200MB: On disk, grpc takes up 250MB when cloned even
  though the tarball of the git repo is 3.2MB. By never using git
  externals, we save on network.

- Consume less cpu: Cloning git repositories is much slower than
  downloading and extracting a tarball.
Change: 133895791

1 files changed, 34 insertions, 55 deletions

diff --git a/gif.BUILD b/gif.BUILD
index 892e109e7d..22ccda52e4 100644
--- a/gif.BUILD
+++ b/gif.BUILD
@@ -1,65 +1,44 @@
-SOURCES = [
-    "dgif_lib.c",
-    "egif_lib.c",
-    "gif_font.c",
-    "gif_hash.c",
-    "gifalloc.c",
-    "openbsd-reallocarray.c",
-    "gif_err.c",
-    "quantize.c",
-]
+# Description:
+#   A library for decoding and encoding GIF images
 
-HEADERS = [
-    "gif_hash.h",
-    "gif_lib.h",
-    "gif_lib_private.h",
-]
+licenses(["notice"])  # MIT
 
-config_setting(
-        name = "windows",
-        values = {
-            "cpu": "x64_windows_msvc",
-        },
-        visibility = ["//visibility:public"],
+cc_library(
+    name = "gif",
+    srcs = [
+        "dgif_lib.c",
+        "egif_lib.c",
+        "gif_err.c",
+        "gif_font.c",
+        "gif_hash.c",
+        "gif_hash.h",
+        "gif_lib_private.h",
+        "gifalloc.c",
+        "openbsd-reallocarray.c",
+        "quantize.c",
+    ],
+    hdrs = ["gif_lib.h"],
+    includes = ["."],
+    visibility = ["//visibility:public"],
+    deps = select({
+        ":windows": [":windows_polyfill"],
+        "//conditions:default": [],
+    }),
 )
 
-prefix_dir = "giflib-5.1.4/lib"
-prefix_dir_windows = "windows/giflib-5.1.4/lib"
-
-genrule(
-  name = "srcs_without_unistd",
-  srcs = [prefix_dir + "/" + source for source in SOURCES],
-  outs = [prefix_dir_windows + "/" + source for source in SOURCES],
-  cmd = "for f in $(SRCS); do " +
-        "  sed 's/#include <unistd.h>//g' $$f > $(@D)/%s/$$(basename $$f);" % prefix_dir_windows +
-        "done",
+cc_library(
+    name = "windows_polyfill",
+    hdrs = ["windows/unistd.h"],
+    includes = ["windows"],
 )
 
 genrule(
-  name = "hdrs_without_unistd",
-  srcs = [prefix_dir + "/" + hdrs for hdrs in HEADERS],
-  outs = [prefix_dir_windows + "/" + hdrs for hdrs in HEADERS],
-  cmd = "for f in $(SRCS); do " +
-        "  sed 's/#include <unistd.h>//g' $$f > $(@D)/%s/$$(basename $$f);" % prefix_dir_windows +
-        "done",
+    name = "windows_unistd_h",
+    outs = ["windows/unistd.h"],
+    cmd = "touch $@",
 )
 
-cc_library(
-    name = "gif",
-    srcs = select({
-        "//conditions:default" : [prefix_dir + "/" + source for source in SOURCES],
-        ":windows" : [":srcs_without_unistd"],
-    }),
-    hdrs = select({
-        "//conditions:default" : [prefix_dir + "/" + hdrs for hdrs in HEADERS],
-        ":windows" : [":hdrs_without_unistd"],
-    }),
-    includes = select({
-        "//conditions:default" : [prefix_dir],
-        ":windows" : [prefix_dir_windows],
-    }),
-    defines = [
-        "HAVE_CONFIG_H",
-    ],
-    visibility = ["//visibility:public"],
+config_setting(
+    name = "windows",
+    values = {"cpu": "x64_windows_msvc"},
 )