build: ensure proper capitalization of R and RScript

These scripts previously worked on macOS, but not on Linux. This was
due to Apple's case-insensitive file system. This commit ensures that
the executables are properly capitalized.

The commit also removes unused usage information functions as
shellcheck was complaining about them.

Author: Planeshifter

tools/scripts/check_lintr

@@ -24,18 +24,9 @@
 # VARIABLES #
 
 # Find Rscript:
-RSCRIPT=$(command -v rscript 2>/dev/null)
+RSCRIPT=$(command -v Rscript 2>/dev/null)
 
 
-# FUNCTIONS #
-
-# Prints usage information.
-usage() {
-	echo '' >&2
-	echo 'Usage: check_lintr' >&2
-	echo '' >&2
-}
-
 # MAIN #
 
 if [[ -x "${RSCRIPT}" ]] && "${RSCRIPT}" -e 'packageVersion("lintr")' &>/dev/null; then

tools/scripts/check_rscript

@@ -24,18 +24,9 @@
 # VARIABLES #
 
 # Find Rscript:
-RSCRIPT=$(command -v rscript 2>/dev/null)
+RSCRIPT=$(command -v Rscript 2>/dev/null)
 
 
-# FUNCTIONS #
-
-# Prints usage information.
-usage() {
-	echo '' >&2
-	echo 'Usage: check_rscript' >&2
-	echo '' >&2
-}
-
 # MAIN #
 
 if [[ -x "${RSCRIPT}" ]] && "${RSCRIPT}" --version >/dev/null; then

tools/scripts/deps_info

@@ -21,15 +21,6 @@
 # Usage: deps_info
 #
 
-# FUNCTIONS #
-
-# Prints usage information.
-usage() {
-	echo '' >&2
-	echo 'Usage: deps_info' >&2
-	echo '' >&2
-}
-
 # MAIN #
 
 CLANG=$(command -v clang 2>/dev/null)
@@ -142,7 +133,7 @@ else
 fi
 echo '' >&2
 
-RSCRIPT=$(command -v rscript 2>/dev/null)
+RSCRIPT=$(command -v Rscript 2>/dev/null)
 echo '-----'
 echo 'lintr:' >&2
 echo '' >&2
@@ -252,7 +243,7 @@ else
 fi
 echo '' >&2
 
-R=$(command -v r 2>/dev/null)
+R=$(command -v R 2>/dev/null)
 echo '-----'
 echo 'R:' >&2
 echo '' >&2
@@ -263,7 +254,7 @@ else
 fi
 echo '' >&2
 
-RSCRIPT=$(command -v rscript 2>/dev/null)
+RSCRIPT=$(command -v Rscript 2>/dev/null)
 echo '-----'
 echo 'Rscript:' >&2
 echo '' >&2