iOS, bump versions

SDK needed is 11.3
Xcode needed is 9.3

Change-Id: If26eda81f969f63500d94e3274dda8efb59dec12

README.md

@@ -42,8 +42,8 @@ run and compile LibreOffice, also used by the TDF builds:
     * Runtime: RHEL 6 or CentOS 6
     * Build: GCC 4.8.1 or Clang
 * iOS (only for LibreOfficeKit):
-    * Runtime: 11.2 (only support for newer i devices == 64 bit)
-    * Build: Xcode 9.0 and iPhone SDK 11.2
+    * Runtime: 11.3 (only support for newer i devices == 64 bit)
+    * Build: Xcode 9.3 and iPhone SDK 11.3
 
 At least Clang 3.4.2 is known to be too old to pass the configure.ac check "whether $CXX supports
 C++17, C++14, or C++11" in its current form (due to the #pragma GCC diagnostic ignored "-Wpragmas"

configure.ac

@@ -2925,7 +2925,7 @@ dnl ===================================================================
 
 if test $_os = iOS; then
     AC_MSG_CHECKING([what iOS SDK to use])
-    current_sdk_ver=11.2
+    current_sdk_ver=11.3
     if test "$enable_ios_simulator" = "yes"; then
         platform=iPhoneSimulator
         versionmin=-mios-simulator-version-min=$current_sdk_ver