should elf_image be mmap-ed with +X?

[mustime]

Having realized that library loaded by WDynamicLibOpen with memory protection readonly.

whale/whale/src/platform/linux/elf_image.cc

Line 195 in 43debbb

base_ = mmap(nullptr, len_, PROT_READ, MAP_PRIVATE, fd, 0);

There is a possible scenario, if the target library is not already loaded in current process, i.e, whale::FindExecuteMemoryRange returns empty whale::MemoryRange. And the library would be loaded by WDynamicLibOpen with readonly protection. Therefore the function resolved by WDynamicLibSymbol should be resided in the same readonly region, causing an attempted call of these functions to raise segment fault error.