Disable PCRE JIT on iOS

First of all, we were missing an implementation of SLJIT_CACHE_FLUSH,
as ___clear_cache was not available and we would get missing symbols.

This was fixed in upstream PCRE 8.31, but even then the JIT would
only work on jailbroken devices, so we disable it.

http://bugs.exim.org/show_bug.cgi?id=1243

Change-Id: I678f9a31eb76d7d08882465befb9d799e46e7cf8
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

src/3rdparty/pcre.pri

@@ -1,6 +1,7 @@
 DEFINES += PCRE_HAVE_CONFIG_H
 
 win32:DEFINES += PCRE_STATIC
+ios:DEFINES += PCRE_DISABLE_JIT
 
 INCLUDEPATH += $$PWD/pcre
 SOURCES += \

src/3rdparty/pcre/config.h

@@ -20,7 +20,7 @@
     - x86/x86-64
     - MIPS 32bit (__GNUC__ compilers only)
 */
-#if \
+#if !defined(PCRE_DISABLE_JIT) && (\
     /* ARM */ \
     (defined(__GNUC__) && (defined(__arm__) || defined(__TARGET_ARCH_ARM))) \
     /* x86 32/64 */ \
@@ -29,6 +29,6 @@
     /* MIPS32 */ \
     || (defined(__GNUC__) \
        && (defined(__mips) || defined(__mips__)) \
-       && !(defined(_MIPS_ARCH_MIPS64) || defined(__mips64)))
+       && !(defined(_MIPS_ARCH_MIPS64) || defined(__mips64))))
 #  define SUPPORT_JIT
 #endif