install_deps: Enable PIC in Python static library.

Update for D3078, I think it should be fixed

Benefits:
- after installing python 3.7 with `./build_files/build_environment/install_deps.sh`, user will be able to run `make bpy` without linking error:
  - https://blender.stackexchange.com/questions/102933/a-working-guidance-for-building-blender-as-bpy-python-module
  - https://stackoverflow.com/questions/36779834/compiling-blender-bpy-recompile-with-fpic

To prevent errors like `/opt/lib/python-3.7.4/bin/python3.7: error while loading shared libraries: libpython3.7m.so.1.0: cannot open shared object file: No such file or directory`, add python .so lib to ldconfig

Reviewed By: mont29

Differential Revision: https://developer.blender.org/D7177

build_files/build_environment/install_deps.sh

@@ -1289,7 +1289,7 @@ compile_Python() {
 
     ./configure --prefix=$_inst --libdir=$_inst/lib --enable-ipv6 \
         --enable-loadable-sqlite-extensions --with-dbmliborder=bdb \
-        --with-computed-gotos --with-pymalloc
+        --with-computed-gotos --with-pymalloc --enable-shared
 
     make -j$THREADS && make install
     make clean
@@ -1310,6 +1310,8 @@ compile_Python() {
     INFO "Own Python-$PYTHON_VERSION is up to date, nothing to do!"
     INFO "If you want to force rebuild of this lib, use the --force-python option."
   fi
+
+  run_ldconfig "python-$PYTHON_VERSION_MIN"
 }
 
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