Revert "More fixes related to spaces in paths"

This commit was breaking the detection of slicot. My understanding is that
autoconf is not able to deal with spaces in paths, hence Windows users have not
choice but to use the 8.3 notation for MATLAB location.

This reverts commit 4ab79c55.

(cherry picked from commit 40362789)

m4/ax_mexopts.m4

@@ -26,7 +26,7 @@ AX_COMPARE_VERSION([$MATLAB_VERSION], [lt], [7.5], [AC_MSG_ERROR([Your MATLAB is
 
 AC_MSG_CHECKING([for options to compile MEX for MATLAB])
 
-MATLAB_CPPFLAGS="-I\"$MATLAB\"/extern/include"
+MATLAB_CPPFLAGS="-I$MATLAB/extern/include"
 
 case ${MATLAB_ARCH} in
   glnx86 | glnxa64)
@@ -34,8 +34,8 @@ case ${MATLAB_ARCH} in
     MATLAB_CFLAGS="-fexceptions -fPIC -pthread -g -O2"
     MATLAB_CXXFLAGS="-fPIC -pthread -g -O2"
     MATLAB_FFLAGS="-fPIC -g -O2 -fexceptions"
-    MATLAB_LDFLAGS_NOMAP="-shared -Wl,--no-undefined -Wl,-rpath-link,\"$MATLAB\"/bin/${MATLAB_ARCH} -L\"$MATLAB\"/bin/${MATLAB_ARCH}"
-    MATLAB_LDFLAGS="$MATLAB_LDFLAGS_NOMAP -Wl,--version-script,\"$MATLAB\"/extern/lib/${MATLAB_ARCH}/mexFunction.map"
+    MATLAB_LDFLAGS_NOMAP="-shared -Wl,--no-undefined -Wl,-rpath-link,$MATLAB/bin/${MATLAB_ARCH} -L$MATLAB/bin/${MATLAB_ARCH}"
+    MATLAB_LDFLAGS="$MATLAB_LDFLAGS_NOMAP -Wl,--version-script,$MATLAB/extern/lib/${MATLAB_ARCH}/mexFunction.map"
     MATLAB_LIBS="-lmx -lmex -lmat -lm -lstdc++ -lmwlapack -lmwblas"
     if test "${MATLAB_ARCH}" = "glnx86"; then
       MATLAB_DEFS="$MATLAB_DEFS -D_FILE_OFFSET_BITS=64"
@@ -53,8 +53,8 @@ case ${MATLAB_ARCH} in
     MATLAB_FFLAGS="-fexceptions -g -O2 -fno-underscoring"
     MATLAB_DEFS="$MATLAB_DEFS -DNDEBUG"
     # Note that static-libstdc++ is only supported since GCC 4.5 (but generates no error on older versions)
-    MATLAB_LDFLAGS_NOMAP="-static-libgcc -static-libstdc++ -shared -L\"$MATLAB\"/bin/${MATLAB_ARCH}"
-    MATLAB_LDFLAGS="$MATLAB_LDFLAGS_NOMAP \"$(pwd)\"/$srcdir/mex.def"
+    MATLAB_LDFLAGS_NOMAP="-static-libgcc -static-libstdc++ -shared -L$MATLAB/bin/${MATLAB_ARCH}"
+    MATLAB_LDFLAGS="$MATLAB_LDFLAGS_NOMAP $(pwd)/$srcdir/mex.def"
     MATLAB_LIBS="-lmex -lmx -lmat -lmwlapack -lmwblas"
     ax_mexopts_ok="yes"
     ;;
@@ -69,8 +69,8 @@ case ${MATLAB_ARCH} in
     MATLAB_CFLAGS="-fno-common -arch $ARCHS -mmacosx-version-min=$MACOSX_DEPLOYMENT_TARGET -fexceptions"
     MATLAB_CXXFLAGS="-fno-common -fexceptions -arch $ARCHS -mmacosx-version-min=$MACOSX_DEPLOYMENT_TARGET"
     MATLAB_FFLAGS="-fexceptions -fbackslash -arch $ARCHS"
-    MATLAB_LDFLAGS_NOMAP="-L\"$MATLAB\"/bin/${MATLAB_ARCH} -Wl,-twolevel_namespace -undefined error -arch $ARCHS -mmacosx-version-min=$MACOSX_DEPLOYMENT_TARGET -bundle"
-    MATLAB_LDFLAGS="$MATLAB_LDFLAGS_NOMAP -Wl,-exported_symbols_list,\"$(pwd)\"/$srcdir/mexFunction-MacOSX.map"
+    MATLAB_LDFLAGS_NOMAP="-L$MATLAB/bin/${MATLAB_ARCH} -Wl,-twolevel_namespace -undefined error -arch $ARCHS -mmacosx-version-min=$MACOSX_DEPLOYMENT_TARGET -bundle"
+    MATLAB_LDFLAGS="$MATLAB_LDFLAGS_NOMAP -Wl,-exported_symbols_list,$(pwd)/$srcdir/mexFunction-MacOSX.map"
     MATLAB_LIBS="-lmx -lmex -lmat -lstdc++ -lmwlapack -lmwblas"
     ax_mexopts_ok="yes"
     ;;
@@ -86,9 +86,9 @@ fi
 
 # Converts the MATLAB version number into comparable integers with only major and minor version numbers
 # For example, 7.4.2 will become 0704
-ax_matlab_ver=$(echo "$MATLAB_VERSION" | $SED -e 's/\([[0-9]]*\)\.\([[0-9]]*\).*/Z\1ZZ\2Z/' \
-                                              -e 's/Z\([[0-9]]\)Z/Z0\1Z/g' \
-                                              -e 's/[[^0-9]]//g')
+ax_matlab_ver=`echo "$MATLAB_VERSION" | $SED -e 's/\([[0-9]]*\)\.\([[0-9]]*\).*/Z\1ZZ\2Z/' \
+                                             -e 's/Z\([[0-9]]\)Z/Z0\1Z/g' \
+                                             -e 's/[[^0-9]]//g'`
 
 MATLAB_DEFS="$MATLAB_DEFS -DMATLAB_VERSION=0x${ax_matlab_ver}"