Rename rgrep to rsgrep

rgrep is a common alias for 'grep -r' and this new macro was confusing.

Test: cd external/rust/crates
    rsgrep test
Change-Id: If71cdcc926455983a04a80982356e9feb61968fe
diff --git a/envsetup.sh b/envsetup.sh
index a5f6b6d..15d6fb4 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -27,7 +27,7 @@
 - mangrep:    Greps on all local AndroidManifest.xml files.
 - mgrep:      Greps on all local Makefiles and *.bp files.
 - owngrep:    Greps on all local OWNERS files.
-- rgrep:      Greps on all local Rust files.
+- rsgrep:     Greps on all local Rust files.
 - sepgrep:    Greps on all local sepolicy files.
 - sgrep:      Greps on all local source files.
 - godir:      Go to the directory containing a file.
@@ -1038,7 +1038,7 @@
         -exec grep --color -n "$@" {} +
 }
 
-function rgrep()
+function rsgrep()
 {
     find . -name .repo -prune -o -name .git -prune -o -name out -prune -o -type f -name "*\.rs" \
         -exec grep --color -n "$@" {} +