rtl: starts-/endsWith* new second parameter since 4.2

Updated the documentation for the new optional second parameter in the
O(U)String startsWith* and endsWith* methods so it is explicitly said
that it is only available since LibreOffice 4.2

Change-Id: I58758e4bae85eef07c578dd50d6e0279b49deaf5
Reviewed-on: https://gerrit.libreoffice.org/6649Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>

include/rtl/string.hxx

@@ -682,7 +682,8 @@ public:
       @param str the substring to be compared
 
       @param rest if non-null, and this function returns true, then assign a
-      copy of the remainder of this string to *rest
+      copy of the remainder of this string to *rest. Available since
+      LibreOffice 4.2
 
       @return true if and only if the given str appears as a substring at the
       start of this string
@@ -720,7 +721,8 @@ public:
       @param str the substring to be compared
 
       @param rest if non-null, and this function returns true, then assign a
-      copy of the remainder of this string to *rest
+      copy of the remainder of this string to *rest. Available since
+      LibreOffice 4.2
 
       @return true if and only if the given str appears as a substring at the
       end of this string

include/rtl/ustring.hxx

@@ -923,7 +923,8 @@ public:
       @param str the substring to be compared
 
       @param rest if non-null, and this function returns true, then assign a
-      copy of the remainder of this string to *rest
+      copy of the remainder of this string to *rest. Available since
+      LibreOffice 4.2
 
       @return true if and only if the given str appears as a substring at the
       start of this string
@@ -968,7 +969,8 @@ public:
       @param str the substring to be compared
 
       @param rest if non-null, and this function returns true, then assign a
-      copy of the remainder of this string to *rest
+      copy of the remainder of this string to *rest. Available since
+      LibreOffice 4.2
 
       @return true if and only if the given str appears as a substring at the
       start of this string, ignoring the case of ASCII letters ("A"--"Z" and
@@ -1013,7 +1015,8 @@ public:
       @param str the substring to be compared
 
       @param rest if non-null, and this function returns true, then assign a
-      copy of the remainder of this string to *rest
+      copy of the remainder of this string to *rest. Available since
+      LibreOffice 4.2
 
       @return true if and only if the given str appears as a substring at the
       end of this string
@@ -1083,7 +1086,8 @@ public:
       @param str the substring to be compared
 
       @param rest if non-null, and this function returns true, then assign a
-      copy of the remainder of this string to *rest
+      copy of the remainder of this string to *rest. Available since
+      LibreOffice 4.2
 
       @return true if and only if the given str appears as a substring at the
       end of this string, ignoring the case of ASCII letters ("A"--"Z" and