getGccPaths returns empty seq
Code to reproduce:

```nim
import os
import nimterop/cimport
import nimterop/build

static:
  cDebug()
  cDisableCaching()

echo getCompiler()
echo getGccModeArg("c")
echo getGccPaths("c")
let cmd = getCompiler() & " -Wp,-v " & getGccModeArg("c") & " /dev/null"
echo cmd
echo execShellCmd cmd
```

Result:

```bash
$ nim c -r test.nim
Hint: used config file '/etc/nim/nim.cfg' [Conf]
Hint: used config file '/etc/nim/config.nims' [Conf]
............................................
Hint:  [Link]
Hint: 127945 lines; 0.626s; 94.531MiB peakmem; Debug build; proj: /home/unikum/Projects/Nim/nim-uchardet/uchardet/test.nim; out: /home/unikum/Projects/Nim/nim-uchardet/uchardet/test [SuccessX]
Hint: /home/unikum/Projects/Nim/nim-uchardet/uchardet/test  [Exec]
gcc
-xc
@[]
gcc -Wp,-v -xc /dev/null
несуществующий каталог "/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/include" проигнорирован
порядок поиска для #include "...":
порядок поиска для #include <...>:
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include
 /usr/local/include
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include-fixed
 /usr/include
Конец списка поиска.
/usr/sbin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../lib/Scrt1.o: в функции «_start»:
(.text+0x24): неопределённая ссылка на «main»
collect2: ошибка: выполнение ld завершилось с кодом возврата 1
1
```
with `LANG=C` seems works:

```bash
$ LANG=C nim c -r test.nim
Hint: used config file '/etc/nim/nim.cfg' [Conf]
Hint: used config file '/etc/nim/config.nims' [Conf]
............................................CC: test.nim

Hint:  [Link]
Hint: 127945 lines; 0.727s; 94.215MiB peakmem; Debug build; proj: /home/unikum/Projects/Nim/nim-uchardet/test.nim; out: /home/unikum/Projects/Nim/nim-uchardet/test [SuccessX]
Hint: /home/unikum/Projects/Nim/nim-uchardet/test  [Exec]
gcc
-xc
@["/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include", "/usr/local/include", "/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include-fixed", "/usr/include"]
gcc -Wp,-v -xc /dev/null
ignoring nonexistent directory "/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include
 /usr/local/include
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include-fixed
 /usr/include
End of search list.
/usr/sbin/ld: /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../lib/Scrt1.o: in function `_start':
(.text+0x24): undefined reference to `main'
collect2: error: ld returned 1 exit status
1
```
Additional info:

```bash
$ cat /etc/os-release
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
BUILD_ID=rolling
ANSI_COLOR="38;2;23;147;209"
HOME_URL="https://www.archlinux.org/"
DOCUMENTATION_URL="https://wiki.archlinux.org/"
SUPPORT_URL="https://bbs.archlinux.org/"
BUG_REPORT_URL="https://bugs.archlinux.org/"
LOGO=archlinux
$LANG=C gcc -v
Using built-in specs.
COLLECT_GCC=/usr/sbin/gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++,d --with-isl --with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-install-libiberty --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch --disable-libunwind-exceptions --disable-werror gdc_include_dir=/usr/include/dlang/gdc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.2.0 (GCC) 
