testsuite: Rename a few C++ to .C or .cc.

The tests are C++ code, so use a proper file extension.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/boolcomplex-1.c: Moved to...
	* g++.dg/ext/boolcomplex-1.C: ...here.
	* g++.dg/opt/pr47639.c: Moved to...
	* g++.dg/opt/pr47639.C: ...here.
	* g++.dg/pr83979.c: Moved to...
	* g++.dg/pr83979.C: ...here.
	* g++.dg/tm/asm-1.c: Moved to...
	* g++.dg/tm/asm-1.C: ...here.
	* g++.dg/vect/pr71483.c: Moved to...
	* g++.dg/vect/pr71483.cc: ...here.

diff --git a/gcc/testsuite/g++.dg/ext/boolcomplex-1.c b/gcc/testsuite/g++.dg/ext/boolcomplex-1.C
similarity index 100%
rename from gcc/testsuite/g++.dg/ext/boolcomplex-1.c
rename to gcc/testsuite/g++.dg/ext/boolcomplex-1.C

diff --git a/gcc/testsuite/g++.dg/opt/pr47639.c b/gcc/testsuite/g++.dg/opt/pr47639.C
similarity index 100%
rename from gcc/testsuite/g++.dg/opt/pr47639.c
rename to gcc/testsuite/g++.dg/opt/pr47639.C

diff --git a/gcc/testsuite/g++.dg/pr83979.c b/gcc/testsuite/g++.dg/pr83979.C
similarity index 100%
rename from gcc/testsuite/g++.dg/pr83979.c
rename to gcc/testsuite/g++.dg/pr83979.C

diff --git a/gcc/testsuite/g++.dg/tm/asm-1.c b/gcc/testsuite/g++.dg/tm/asm-1.C
similarity index 100%
rename from gcc/testsuite/g++.dg/tm/asm-1.c
rename to gcc/testsuite/g++.dg/tm/asm-1.C

diff --git a/gcc/testsuite/g++.dg/vect/pr71483.c b/gcc/testsuite/g++.dg/vect/pr71483.cc
similarity index 100%
rename from gcc/testsuite/g++.dg/vect/pr71483.c
rename to gcc/testsuite/g++.dg/vect/pr71483.cc