ARROW-7832: [R] Patches to 0.16.0 release

Closes #6404 from nealrichardson/r-0.16.0.1 and squashes the following commits:

a4fbc20 <Neal Richardson> Fix indentation
46b15eb <Neal Richardson> Changes for CRAN 0.16.0.1

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>

r/README.md

@@ -88,19 +88,17 @@ tab$x
 #>   10
 #> ]
 as.data.frame(tab)
-#> # A tibble: 10 x 3
-#>        x        y z    
-#>    <int>    <dbl> <fct>
-#>  1     1 -0.546   b    
-#>  2     2  0.537   c    
-#>  3     3  0.420   b    
-#>  4     4 -0.584   c    
-#>  5     5  0.847   b    
-#>  6     6  0.266   c    
-#>  7     7  0.445   b    
-#>  8     8 -0.466   c    
-#>  9     9 -0.848   b    
-#> 10    10  0.00231 c
+#>     x            y z
+#> 1   1 -0.545880758 b
+#> 2   2  0.536585304 c
+#> 3   3  0.419623149 b
+#> 4   4 -0.583627199 c
+#> 5   5  0.847460017 b
+#> 6   6  0.266021979 c
+#> 7   7  0.444585270 b
+#> 8   8 -0.466495124 c
+#> 9   9 -0.848370044 b
+#> 10 10  0.002311942 c
 ```
 
 ## Installing a development version

r/configure

@@ -94,7 +94,8 @@ else
       PKG_CFLAGS="-I$BREWDIR/opt/$PKG_BREW_NAME/include"
       PKG_LIBS="-L$BREWDIR/opt/$PKG_BREW_NAME/lib $PKG_LIBS"
     elif [ "$UNAME" = "Linux" ]; then
-      VERSION=$(grep ^Version DESCRIPTION | sed s/Version:\ //)
+      VERSION=`grep ^Version DESCRIPTION | sed s/Version:\ //`
+      : ${LIBARROW_BINARY_DISTRO:="$NOT_CRAN"}
       ${R_HOME}/bin/Rscript tools/linuxlibs.R $VERSION
       PKG_CFLAGS="-I$(pwd)/libarrow/arrow-${VERSION}/include $PKG_CFLAGS"
       PKG_LIBS="-L$(pwd)/libarrow/arrow-${VERSION}/lib $PKG_LIBS"

r/tools/linuxlibs.R

@@ -66,22 +66,20 @@ download_binary <- function(os = identify_os()) {
   libfile
 }
 
-# Function to figure out which flavor of binary we should download.
-# By default, it will try to discover from the OS what distro-version we're on
+# Function to figure out which flavor of binary we should download, if at all.
+# By default ("FALSE"), it will not download a precompiled library,
 # but you can override this by setting the env var LIBARROW_BINARY_DISTRO to:
-# * `FALSE` (not case-sensitive), which tells the script not to download a binary,
+# * `TRUE` (not case-sensitive), to try to discover your current OS, or
 # * some other string, presumably a related "distro-version" that has binaries
 #   built that work for your OS
-identify_os <- function(os = Sys.getenv("LIBARROW_BINARY_DISTRO")) {
-  if (nzchar(os)) {
-    if (identical(tolower(os), "false")) {
-      # Env var says not to download a binary
-      return(NULL)
-    } else {
-      # Env var provided an os-version to use--maybe you're on Ubuntu 18.10 but
-      # we only build for 18.04 and that's fine--so use what the user set
-      return(os)
-    }
+identify_os <- function(os = Sys.getenv("LIBARROW_BINARY_DISTRO", "false")) {
+  if (identical(tolower(os), "false")) {
+    # Env var says not to download a binary
+    return(NULL)
+  } else if (!identical(tolower(os), "true")) {
+    # Env var provided an os-version to use--maybe you're on Ubuntu 18.10 but
+    # we only build for 18.04 and that's fine--so use what the user set
+    return(os)
   }
 
   if (nzchar(Sys.which("lsb_release"))) {