Make it compile on Musl and fix warnings

[filoozom]

• Make it compile on Musl
  Not quite sure that #if !defined(__linux__) || defined(__GLIBC__) (in strlcpy.h) is the best way to do it, but it works.

• Fix warnings: C++11 requires a space between literal and string macro
  Basically this code for XXXXX = { PRI64d, PRIszu, PRI64u, PRI64x, PRIpdd }:

find . -type f -exec sed -i 's/"XXXXX/" XXXXX/g' {} \;
find . -type f -exec sed -i 's/XXXXX"/XXXXX "/g' {} \;

• Include fcntl.h instead of sys/fcntl.h
fcntl.h was already used in leveldb/util/env_posix.cc and leveldb/db/corruption_test.cc and sys/fcntl.h throws a warning.

• Remove two unused variables
  Those variables weren't used in the code or in some comments, so I removed them instead of commenting them out.

• Fix wrong formats
  %u for CTransaction.nTime, %PRI64d for GetBlockTime().

• Fix misleading indentation

• Use unique_ptr instead of auto_ptr
auto_ptr is deprecated.

• Add default return in exp_n2
  Doesn't change the return value but fixes the following warning:

In file included from hash_magi.h:5:0,
                 from main.h:13,
                 from db.h:8,
                 from main.cpp:8:
magimath.h: In function 'double exp_n2(double, double)':
magimath.h:46:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

• Dynamically allocate x and w in GaussianQuad_N
  Fix the following warning:

magimath.cpp: In function 'double GaussianQuad_N(double (*)(double), double, double, int)':
magimath.cpp:46:8: warning: stack protector not protecting local variables: variable length buffer [-Wstack-protector]
 double GaussianQuad_N(double func(const double), const double a2, const double b2, const int NptGQ)
        ^~~~~~~~~~~~~~

• Explicitely cast subscript to int in util.cpp
  Fix the following warning:

util.cpp: In function 'long int hex2long(const char*)':
util.cpp:503:43: warning: array subscript has type 'char' [-Wchar-subscripts]
   ret = (ret << 4) | hextable[*hexString++];
                                           ^

• Assign default value to nPos in GetClientVersion
  Fix the following warning:

util.cpp: In function 'unsigned int GetClientVersion(int, std::__cxx11::string)':
util.cpp:1399:50: warning: 'nPos' may be used uninitialized in this function [-Wmaybe-uninitialized]
     unsigned int nVersion = nClientVersion * 10, nPos;
                                                  ^~~~

[ovpn-to]

great work!

this commit throwing error:
16c7511

tested @ debian 9 stretch x64

make -f makefile.unix
/bin/sh ../share/genbuild.sh obj/build.h
g++ -c -O2 -pthread -Wall -Wextra -Wformat -Wformat-security -Wno-unused-parameter -g -DBOOST_SPIRIT_THREADSAFE -I/mnt/gits/eqcore/src -I/mnt/gits/eqcore/src/hash -I/mnt/gits/eqcore/src/obj -DUSE_UPNP=0 -DUSE_IPV6=1 -I/mnt/gits/eqcore/src/leveldb/include -I/mnt/gits/eqcore/src/leveldb/helpers -DHAVE_BUILD_INFO -fno-stack-protector -fstack-protector-all -Wstack-protector -D_FORTIFY_SOURCE=2 -msse2 -MMD -MF obj/netbase.d -o obj/netbase.o netbase.cpp
In file included from netbase.cpp:15:0:
strlcpy.h:16:0: error: unterminated #ifndef
#ifndef BITCOIN_STRLCPY_H

makefile.unix:186: recipe for target 'obj/netbase.o' failed
make: *** [obj/netbase.o] Error 1

[filoozom]

Did you apply this commit too: b0264b0? Should work.