[Android] Enable LTO

At least on arm64 it appears to work just fine, but other archs need testing as
well.

firebird.pro

@@ -51,7 +51,7 @@ QMAKE_CXXFLAGS_RELEASE = -O3 -DNDEBUG
 # Don't enable LTO with clang on Linux, incompatible with Qt (QTBUG-43556).
 # On FreeBSD, clang with LTO produces copy relocs, which are incompatible
 # with Qt's -reduce-relocations option (QTBUG-86173).
-!clang | !if(linux|freebsd): CONFIG += ltcg
+!clang | !if(if(linux:!android)|freebsd): CONFIG += ltcg
 
 # noexecstack is not supported by MinGW's as
 !win32 {