Add "untrusted" sections for environment variables defined in Occlum.json. Environment
variable defined in "default" will be shown in libos directly. Environment variable
defined in "untrusted" can be passed from occlum run or PAL layer and can override
the value in "default" and thus is considered "untrusted".
1. Now we support set App's env in Occlum.json, for example:
"env": [
"OCCLUM=yes",
"TEST=true"
]
2. Rewrite env test cases
3. Update Dockerfile to install "jq" tool
The old system call mechanism works by relocating the symbol __occlum_syscall
provided by libocclum_stub.so to the real entry point of the LibOS. This symbol
relocation is done by the program loader. Now, the new system call mechanism is
based on passing the entry point via the auxiliary vector. This new mechanism
is simpler and is more compatible with the upcoming support for ld.so.
Changes:
1. Fix a bug in serializing auxiliary vector in the stack of a user program;
2. Passing syscall entry via auxiliary vector;
3. Remove relocating for the __occlum_syscall symbol;
4. Remove the dependency on libocclum_stub.so in tests.
