Why does not this plugin set the '-pthread' flag of GCC?

[kimkim1...@yahoo.co.jp]

Hello

I download 'Pkg-config support for Eclipse CDT' from Update site 'https://raw.githubusercontent.com/TuononenP/pkg-config.p2/master/site.xml' and use it.
Why does not this plugin set the '-pthread' flag of GCC? Please give me some advice.
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'https://marketplace.eclipse.org/content/pkg-config-support-eclipse-cdt#group-details' is written as follows.
"Pkg-config support will set compiler and linker flags automatically that GCC needs to build selected packages - specifically includes, libraries, and some other GCC flags.
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The following is the output of the pkg-config command.
$ pkg-config-cflags gtk + -3.0
- I / usr / include / gtk - 3.0 - I / usr / include / pango - 1.0 - I / usr / include / glib - 2.0 - I / usr / lib 64 / glib - 2.0 / include - I / usr / include / cairo - I / usr / include / pixman - 1 - I / usr / include / freetype 2 - I / usr / include / libpng 16 - I / usr / include / harfbuzz - I / usr / include / gdk - pixbuf - 2.0 - I / usr / usr / include / atk - 1.0 - I / usr / include / at - spi 2 - atk / 2.0 - I / usr / include / at - spi - 2.0 - I / usr / include / dbus-1.0-I / usr / lib64 / dbus-1.0 / include -pthread
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My development environment:
  Fedora: release 27 (Twenty Seven)
  eclipse: Oxygen.2 (4.7.2)
  Eclipse C/C++ Development Tools: 9.4.0.201801311351
  Locale: ja_JP.UTF-8
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Thanks and Best regards.