bootstrap: Re-implement command line option processing

Use POSIX shell features to shorten and simplify bootstrap command-line
option processing.

bootstrap

@@ -11,6 +11,10 @@
 # See the License for more information.
 #=============================================================================
 
+die() {
+  echo "$@" 1>&2 ; exit 1
+}
+
 # Version number extraction function.
 cmake_version_component()
 {
@@ -527,63 +531,30 @@ cmake_verbose=
 cmake_parallel_make=
 cmake_ccache_enabled=
 cmake_prefix_dir="${cmake_default_prefix}"
-for a in "$@"; do
-  if echo $a | grep "^--prefix=" > /dev/null 2> /dev/null; then
-    cmake_prefix_dir=`echo $a | sed "s/^--prefix=//"`
-    cmake_prefix_dir=`cmake_fix_slashes "${cmake_prefix_dir}"`
-  fi
-  if echo $a | grep "^--parallel=" > /dev/null 2> /dev/null; then
-    cmake_parallel_make=`echo $a | sed "s/^--parallel=//" | grep "[0-9][0-9]*"`
-  fi
-  if echo $a | grep "^--datadir=" > /dev/null 2> /dev/null; then
-    cmake_data_dir=`echo $a | sed "s/^--datadir=//"`
-  fi
-  if echo $a | grep "^--docdir=" > /dev/null 2> /dev/null; then
-    cmake_doc_dir=`echo $a | sed "s/^--docdir=//"`
-  fi
-  if echo $a | grep "^--mandir=" > /dev/null 2> /dev/null; then
-    cmake_man_dir=`echo $a | sed "s/^--mandir=//"`
-  fi
-  if echo $a | grep "^--init=" > /dev/null 2> /dev/null; then
-    cmake_init_file=`echo $a | sed "s/^--init=//"`
-  fi
-  for lib in bzip2 curl expat libarchive zlib; do
-    if echo $a | grep "^--system-${lib}" > /dev/null 2> /dev/null; then
-      cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARY_`cmake_toupper ${lib}`=1"
-      break
-    elif echo $a | grep "^--no-system-${lib}" > /dev/null 2> /dev/null; then
-      cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARY_`cmake_toupper ${lib}`=0"
-      break
-    fi
-  done
-  if echo $a | grep "^--system-libs" > /dev/null 2> /dev/null; then
-    cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARIES=1"
-  fi
-  if echo $a | grep "^--no-system-libs" > /dev/null 2> /dev/null; then
-    cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARIES=0"
-  fi
-  if echo $a | grep "^--qt-gui" > /dev/null 2> /dev/null; then
-    cmake_bootstrap_qt_gui="1"
-  fi
-  if echo $a | grep "^--no-qt-gui" > /dev/null 2> /dev/null; then
-    cmake_bootstrap_qt_gui="0"
-  fi
-  if echo $a | grep "^--qt-qmake=" > /dev/null 2> /dev/null; then
-    cmake_bootstrap_qt_qmake=`echo $a | sed "s/^--qt-qmake=//"`
-  fi
-  if echo $a | grep "^--help" > /dev/null 2> /dev/null; then
-    cmake_usage
-  fi
-  if echo $a | grep "^--version" > /dev/null 2> /dev/null; then
-    cmake_version_display
-    exit 2
-  fi
-  if echo $a | grep "^--verbose" > /dev/null 2> /dev/null; then
-    cmake_verbose=TRUE
-  fi
-  if echo $a | grep "^--enable-ccache" > /dev/null 2> /dev/null; then
-    cmake_ccache_enabled=TRUE
-  fi
+while test $# != 0; do
+  case "$1" in
+  --prefix=*) cmake_prefix_dir=`cmake_fix_slashes "${1#*=}"` ;;
+  --parallel=*) cmake_parallel_make="${1#*=}" ;;
+  --datadir=*) cmake_data_dir="${1#*=}" ;;
+  --docdir=*) cmake_doc_dir="${1#*=}" ;;
+  --mandir=*) cmake_man_dir="${1#*=}" ;;
+  --init=*) cmake_init_file="${1#*=}" ;;
+  --system-libs) cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARIES=1" ;;
+  --no-system-libs) cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARIES=0" ;;
+  --system-bzip2|--system-curl|--system-expat|--system-libarchive|--system-zlib)
+    cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARY_`cmake_toupper ${1#--system-}`=1" ;;
+  --no-system-bzip2|--no-system-curl|--no-system-expat|--no-system-libarchive|--no-system-zlib)
+    cmake_bootstrap_system_libs="${cmake_bootstrap_system_libs} -DCMAKE_USE_SYSTEM_LIBRARY_`cmake_toupper ${1#--no-system-}`=0" ;;
+  --qt-gui) cmake_bootstrap_qt_gui="1" ;;
+  --no-qt-gui) cmake_bootstrap_qt_gui="0" ;;
+  --qt-qmake=*) cmake_bootstrap_qt_qmake="${1#*=}" ;;
+  --help) cmake_usage ;;
+  --version) cmake_version_display ; exit 2 ;;
+  --verbose) cmake_verbose=TRUE ;;
+  --enable-ccache) cmake_ccache_enabled=TRUE ;;
+  *) die "Unknown option: $1" ;;
+  esac
+  shift
 done
 
 # If verbose, display some information about bootstrap