[pragma] Allow cast-align in hb-font.cc

../src/hb-machinery.hh: In instantiation of 'const Type& StructAtOffset(const void*, unsigned int) [with Type = unsigned int]':
../src/hb-font.cc:144:85:   required from here
../src/hb-machinery.hh:63:12: error: cast from 'const char*' to 'const unsigned int*' increases required alignment of target type [-Werror=cast-align]
 { return * reinterpret_cast<const Type*> ((const char *) P + offset); }
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/hb-machinery.hh: In instantiation of 'Type& StructAtOffset(void*, unsigned int) [with Type = unsigned int]':
../src/hb-font.cc:145:79:   required from here
../src/hb-machinery.hh:66:12: error: cast from 'char*' to 'unsigned int*' increases required alignment of target type [-Werror=cast-align]
 { return * reinterpret_cast<Type*> ((char *) P + offset); }
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../src/hb-machinery.hh: In instantiation of 'Type& StructAtOffset(void*, unsigned int) [with Type = int]':
1 file changed