Add project config for SonarCloud to ignore some files/rules

These settings have already been configured in the UI, but it might be
helpful to have them here so it's easier to set up the analysis of forks.

sonar-project.properties

@@ -0,0 +1,42 @@
+# exclude these files completely
+sonar.exclusions=\
+	src/manager/templates/static/jquery.js, \
+	src/include/linux/**, \
+	src/frontends/**, \
+	**/data.sql, \
+	**/test.sql, \
+	**/tables.sql, \
+	**/ipsec.sql
+
+# don't report duplications in these files
+sonar.cpd.exclusions=\
+	src/libstrongswan/crypto/proposal/proposal_keywords_static.c, \
+	src/libstrongswan/settings/settings_parser.*, \
+	src/libstrongswan/settings/settings_lexer.c, \
+	src/starter/keywords.c, \
+	src/starter/parser/parser.*, \
+	src/starter/parser/lexer.c, \
+	src/stroke/stroke_keywords.c, \
+	**/suites/test_*.c, \
+	**/data.sql
+
+# the following settings are officially only available via UI
+
+# ignore issues in these generated files
+sonar.issue.ignore.allfile=a1,a2,a3
+sonar.issue.ignore.allfile.a1.fileRegexp=generated by flex
+sonar.issue.ignore.allfile.a2.fileRegexp=made by GNU Bison
+sonar.issue.ignore.allfile.a3.fileRegexp=produced by gperf
+
+# ignore some rules
+sonar.issue.ignore.multicriteria=m1,m2,m3,m4,m5
+sonar.issue.ignore.multicriteria.m1.ruleKey=c:SingleDeclarationPerStatement
+sonar.issue.ignore.multicriteria.m1.resourceKey=**/*
+sonar.issue.ignore.multicriteria.m2.ruleKey=c:FunctionEllipsis
+sonar.issue.ignore.multicriteria.m2.resourceKey=**/*
+sonar.issue.ignore.multicriteria.m3.ruleKey=c:S936
+sonar.issue.ignore.multicriteria.m3.resourceKey=**/*
+sonar.issue.ignore.multicriteria.m4.ruleKey=c:S1172
+sonar.issue.ignore.multicriteria.m4.resourceKey=**/*
+sonar.issue.ignore.multicriteria.m5.ruleKey=plsql:SingleLineCommentsSyntaxCheck
+sonar.issue.ignore.multicriteria.m5.resourceKey=**/*