[source] build: accept gcc/g++ without minor version

[LEDE Commits]

hauke pushed a commit to source.git, branch master:
https://git.lede-project.org/8ee2d3f718c79dc7c2e5e859766e23e8058cf3a6

commit 8ee2d3f718c79dc7c2e5e859766e23e8058cf3a6
Author: Justin Kilpatrick <jkilpatr at redhat.com>
AuthorDate: Sat Nov 25 16:14:59 2017 -0500

    build: accept gcc/g++ without minor version
    
    Build dependency: Please install the GNU C Compiler (gcc) 4.8 or later cc
      -dumpversion | grep -E '(4\.[8-9]|5\.[0-9]|6\.[0-9]|7\.[0-9])'
    Build dependency: Please install the GNU C++ Compiler (g++) 4.8 or later
      g++ -dumpversion | grep -E '(4\.[8-9]|5\.[0-9]|6\.[0-9]|7\.[0-9])'
    
    Prerequisite check failed. Use FORCE=1 to override.
    
    On my Fedora 26 machine gcc and g++ -dumpversion returns a whole number
    '7' failing the regex introduced in commit:
    
    b78de6207f6fc1a9db857942cb89f9fcf730a240
    
    This change makes minor versions optional in the build dependency regex
    for gcc and g++ whenever any minor version would be accepted and the
    whole number version is sufficient as a dependency check. For versions
    4.* a minor version is still required.
    
    Signed-off-by: Justin Kilpatrick <jkilpatr at redhat.com>
---
 include/prereq-build.mk | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/prereq-build.mk b/include/prereq-build.mk
index c6f99a2..d7562b4 100644
--- a/include/prereq-build.mk
+++ b/include/prereq-build.mk
@@ -28,8 +28,8 @@ $(eval $(call TestHostCommand,proper-umask, \
 
 $(eval $(call SetupHostCommand,gcc, \
 	Please install the GNU C Compiler (gcc) 4.8 or later \
-	$(CC) -dumpversion | grep -E '(4\.[8-9]|5\.[0-9]|6\.[0-9]|7\.[0-9])', \
-	gcc -dumpversion | grep -E '(4\.[8-9]|5\.[0-9]|6\.[0-9]|7\.[0-9])', \
+	$(CC) -dumpversion | grep -E '(4\.[8-9]|5\.?[0-9]?|6\.?[0-9]?|7\.?[0-9]?)', \
+	gcc -dumpversion | grep -E '(4\.[8-9]|5\.?[0-9]?|6\.?[0-9]?|7\.?[0-9]?)', \
 	gcc48 --version | grep gcc, \
 	gcc49 --version | grep gcc, \
 	gcc5 --version | grep gcc, \
@@ -45,8 +45,8 @@ $(eval $(call TestHostCommand,working-gcc, \
 
 $(eval $(call SetupHostCommand,g++, \
 	Please install the GNU C++ Compiler (g++) 4.8 or later \
-	$(CXX) -dumpversion | grep -E '(4\.[8-9]|5\.[0-9]|6\.[0-9]|7\.[0-9])', \
-	g++ -dumpversion | grep -E '(4\.[8-9]|5\.[0-9]|6\.[0-9]|7\.[0-9])', \
+	$(CXX) -dumpversion | grep -E '(4\.[8-9]|5\.?[0-9]?|6\.?[0-9]?|7\.?[0-9]?)', \
+	g++ -dumpversion | grep -E '(4\.[8-9]|5\.?[0-9]?|6\.?[0-9]?|7\.?[0-9]?)', \
 	g++48 --version | grep g++, \
 	g++49 --version | grep g++, \
 	g++5 --version | grep g++, \