sqlite: Use brace expansion throughout sqlite's README.chromium

Update bash variables to use brace expansion, as it's more versatile and would
make things more consistent if/when we use more fancy bash in the future.

Reference: https://stackoverflow.com/questions/8748831/when-do-we-need-curly-braces-around-shell-variables

Bug: 936694
Change-Id: Iafcefd60405ac9564a7b36af893fdb5d72e6893d
Reviewed-on: https://chromium-review.googlesource.com/c/1493207
Auto-Submit: Darwin Huang <huangdarwin@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636338}

third_party/sqlite/README.chromium

@@ -82,7 +82,7 @@ cp -r sqlite-src-${BASE}/ src
 find src/ -type f -not -iname "*.db" -not -iname "*.eps" -not -iname "*.ico" \
     -not -iname "*.jpg" -not -iname "*.pfx" -not -iname "*.png" \
     -not -iname "*.tiff" -not -iname "*.vsix" \
-    -exec $GNU_SED --in-place 's/[[:space:]]\+$//' {} \+
+    -exec ${GNU_SED} --in-place 's/[[:space:]]\+$//' {} \+
 git add src/
 git clean -i -d -x src  # Make sure no file is git-ignored.
 git commit -m "Squash: Reset SQLite src/ to sqlite-src-${BASE}."
@@ -156,16 +156,16 @@ export GNU_SED=sed  # OSX: "brew install gnu-sed", then use "gsed" here.
 git new-branch sqlite-new-upstream
 # URL from "Alternative Source Code Formats" at https://sqlite.org/download.html
 curl https://sqlite.org/2018/sqlite-src-${NEW}.zip > upstream.zip
-mkdir sqlite-src-$NEW
-unzip ./upstream.zip -d sqlite-src-$NEW
+mkdir sqlite-src-${NEW}
+unzip ./upstream.zip -d sqlite-src-${NEW}
 rm ./upstream.zip
-mv sqlite-src-$NEW/sqlite-*/* sqlite-src-$NEW/
-rmdir sqlite-src-$NEW/sqlite-*/
-xdg-open sqlite-src-$NEW  # Make sure everything looks right.
+mv sqlite-src-${NEW}/sqlite-*/* sqlite-src-${NEW}/
+rmdir sqlite-src-${NEW}/sqlite-*/
+xdg-open sqlite-src-${NEW}  # Make sure everything looks right.
 
 #### Add the new release code in a separate CL, for code review sanity.
-git add sqlite-src-$NEW  # Committing the code as downloaded, on purpose.
-git clean -i -d -x sqlite-src-$NEW  # Make sure no file is git-ignored.
+git add sqlite-src-${NEW}  # Committing the code as downloaded, on purpose.
+git clean -i -d -x sqlite-src-${NEW}  # Make sure no file is git-ignored.
 git commit -m "sqlite: Add code for release 3.28.0"
 git cl upload  # Have the new code in a separate (impossible to review) CL.
 
@@ -177,7 +177,7 @@ cp -r sqlite-src-${OLD}/ src
 find src/ -type f -not -iname "*.db" -not -iname "*.eps" -not -iname "*.ico" \
     -not -iname "*.jpg" -not -iname "*.pfx" -not -iname "*.png" \
     -not -iname "*.tiff" -not -iname "*.vsix" \
-    -exec $GNU_SED --in-place 's/[[:space:]]\+$//' {} \+
+    -exec ${GNU_SED} --in-place 's/[[:space:]]\+$//' {} \+
 git add src/
 git clean -i -d -x src  # Make sure no file is git-ignored.
 git commit -m "Squash: Reset SQLite src/ to sqlite-src-${OLD}."
@@ -193,13 +193,13 @@ git diff origin/master src/
 git checkout sqlite-old-base
 git new-branch --upstream-current sqlite-new-base
 git rm -rf src
-git checkout sqlite-new-upstream -- sqlite-src-$NEW/
+git checkout sqlite-new-upstream -- sqlite-src-${NEW}/
 git mv sqlite-src-${NEW}/ src
 # Clean up trailing whitespace and CRLF so any patches look clean.
 find src/ -type f -not -iname "*.db" -not -iname "*.eps" -not -iname "*.ico" \
     -not -iname "*.jpg" -not -iname "*.pfx" -not -iname "*.png" \
     -not -iname "*.tiff" -not -iname "*.vsix" \
-    -exec $GNU_SED --in-place 's/[[:space:]]\+$//' {} \+
+    -exec ${GNU_SED} --in-place 's/[[:space:]]\+$//' {} \+
 git add src/
 git clean -i -d -x src  # Make sure no file is git-ignored.
 git commit -m "Squash: Reset SQLite src/ to sqlite-src-${NEW}."